A character says "I think I'm going to be sick" when told discomforting news by a villain. The conversation ends with them implied to have vomited, but it is not shown on-screen.
Kyza is a complicated example, but in summary they are portrayed as a gay-coded cis male in the English version of RD, but in Heroes they are portrayed as a non-binary person with they/them pronouns. This seems to be more of a matter of how people's understanding of different LGBTQ+ groups has changed, and I believe it's different between languages as well. Basically you could argue Kyza is being misgendered either in universe and/or on a meta level.
A character is almost decapitated, but the attempt is thwarted.
A CG still shows a character slumped against a wall in front of a man with a sword while the narration describes the fact this is a scene depicting his murder. It is difficult to tell by looking at the CG still whether the man depicted still has his head.
Towards the end of part one of the playable characters is drugged, it makes him very violent in addition to removing his ability to communicate, not nice
A male character who rarely expresses their emotions can, on a second playthrough, finally be convinced to cry about their tragic past. He is hugged and supported by the person who does so.
A man is depicted as pursuing a woman in the course of their duties as spies on opposite sides of a civil war, but the man has regularly added a sexual dynamic to their relationship which the woman has regularly rebuffed.
The final boss is a goddess, and the late acts discuss how worship of her has been perverted for greed and other mistakes. The actual religion of which she is a part is never explicitly shown, however- characters who represent the goddess are individually "divinely ordained", but there is little evidence of what means the masses use to worship.
A villain has invented drugs that turn people into savages, and is confirmed to have fed this drug to a friendly character off-screen without his knowledge or consent.
A character is depicted as tipsy because he has been consuming alcohol instead of doing the job for which he is paid. This scene occurs in what is explicitly a tavern.
A woman regularly attempts to elicit romantic encounters with a male character, who openly says he is scared of her. Although she does not specify sex as her goal, she is incredibly forward compared to most attempts at romance. One attempt involves the male character attempting to bargain with her for her to let his hand go.
An optional flashback on second playthroughs and beyond shows a mass murder in a burning forest, and the focal character- who is mentioned to have heightened empathy and can literally feel the suffering of people around him- is agitated as he describes his surroundings. No victims of this murder are shown on-screen.
An attempted hanging at the end of Part 2, in an animated cutscene Lucia is seen standing in the gallows with the noose around her neck but a character cuts it in time and she's rescued.
A character gives someone a knife and is subsequently stabbed with it. The game either pans away or fades to white before the stabbing occurs, depending on how the player chooses to deal with this situation, but one permutation comes incredibly close to outright depiction with the timing of the fade.
According to a line in the Japanese script, one character was separated from their parents at a young age. Although the implication is absent from the English script, no alternative explanation is provided as to what happened to her parents.
A character may be sacrificed to attempt to save the nation over which he is King. This is quickly revealed to have been in vain. The character may be saved in a second playthrough, although he will still attempt the sacrifice.
One major character's ability to heal the sick and wounded is referred to as "Sacrifice" because it draws upon her own life force. The player may use this ability in battle.
Among a few plot deaths, there is also an avoidable one that's worth noting; if Calill dies in gameplay, there is a unique scene in which the characters discuss how to break the news to her young daughter.
Sometimes happens as part of gameplay, eg. in Part 2 Chapter 1 Leanne can be picked up and carried off by enemy units, and you have to defeat them quickly to rescue her
Late in the game, Micaiah is possessed by a goddess most of the time, though said goddess is more or less benevolent and Micaiah seems to be a willing vessel for her.
A character announces their intention to take their own life, but is unable to do so themselves, requiring someone else do the actual murder. The player is allowed to choose who will take their life, and only on a second playthrough are they allowed to save them.
The above character's mother plans to commit suicide in response to the above events regardless of whether or not the son has been saved, but is prevented from doing so.
The main villain attempted suicide multiple times and failed, but this is only mentioned as an aside. His motivation for his schemes is to arrange a situation where his death is possible.
Of an indirect variety: Pelleas will order either Micaiah or Tauroneo to kill him in late chapter 3. On New Game+, you can take a third option to refuse to cooperate, resulting in his survival.
A male villain is depicted with long hair and makeup, although no attention is drawn to their appearance in the story itself, and his vices are depicted as greed, selfishness and a lack of understanding about other's perspectives, never vanity.
Heather and Kyza are LGBT characters you can recruit - They can both die, as with all recruitable units in the game. This can be avoided and it's possible to keep them alive to the end
An obese man may be recruited, and the majority of the playable cast expresses scorn for them due to their villainous actions in the last game. Their obesity is played for laughs, although he is depicted as decadent and a glutton.
There are dark skinned characters you can recruit. As with all recruitable units in the game they can die, so it's possible they'll be the first in your playthrough, but it's also possible to keep them alive till the end.
The "Laguz", a race that are half human half animal, are used as an allegory for racism with absolutely no subtlety. Many characters are openly racist towards them, anti-racism is a theme of the game so it comes up a lot.
No but the main couple of the game (Micaiah and Sothe) may cause discomfort - Micaiah met Sothe when he was a child and raised him. In the gacha game they are shown together in wedding attire but are also called "brother and sister". It's possible that they get married in the epilogue of this game, but it can be avoided if you don't get them to an A-Rank support.
Due to the oppressive occupation of Nevassa, the main characters of the game's opening act are depicted as on the run, with no stable housing, for multiple years. It is implied that this situation was not significantly different before the occupation began.