how to train puppy out of barking when told no?

my sister who lives with me and my mother recently got a puppy, named Milo.. I don't even think my sister should have a dog because she never takes Milo out. she literally taught him to pee and poop on puppy pads inside the house because she's too lazy to take him down the few flights of stairs (we live in an apartment), plus she never takes Milo outside for walks or anything. she refuses to train Milo too, both behaviorally and physically. this has caused Milo to have bad behavioral issues, such as biting and barking repeatedly when told no.

I'm only in middle school, but I'm sick of Milo trying to nip/bite me when I say no. it's tiring. is there any way that I can train Milo out of this? should I work on training Milo physically too? if so, how and where should I start? milo only knows sit and lay down.

btw, Milo is a purebred boxer who was born in February 2025.