"Boss, you killed a child. Amazing! Mission complete! That right there is why you're the best, boss. The one and only."

i think Drakengard is too important a game on this front to not include

in the original pathologic one character's first major moral dilemma centers around child murder

You can kill kids in the simulation in Fallout 3 (which also kills them in real life) if you count that

Tyranny
Witcher 3
LISA
Bioshock 2: Minerva's Den
Nier

https://youtu.be/VQJvr9G34L0?t=458

yeah lisa the painful has a gag early on where you burn a bunch of kids to death

Pretty much any Fire Emblem game has a child you can recruit from the enemy side who you can choose to not kill leading to their death forever.

*choose to not recruit and kill them

town with no name has a kid you can shoot within the first minute of gameplay

in live a live if you do the final chapter as the antagonist you can do a boss rush where you kill the protagonists as the bosses, one of which is a young teenager and another is supposed to be like 12

technically postal doesn't have you kill kids since he always misses and goes into a mental breakdown.

in dying light there are baby zombies as enemies that cry a lot and are fucking annoying

The entire SMT series

Also there are no kids in Resident Evil 4

You didn't play RE4 did you?

If Bloodborne counts then Yoshi's Island should too.

Days Gone lets you kill little child zombies