In The Witcher 3: Wild Hunt, you can refer to the following for the ending of The Witcher 3:
Syl's ending can be seen in her background story as a death ending. When the player saw her going to rescue Margarita, they accidentally discovered that Syl was also there. Syl had been tortured by witch hunters and was dying. , so she asked Geralt to let her die with the dignity of a sorceress, so Geralt gave her a ride, which was the ending of death.