This is not simply a LORA to make exposed breasts. It is supposed to make cleavage with exposed nipples.

The important tags are "exposed_nipples" and "cleavage"

I don't know if "nude, naked, topless" is necessary in the negative but I always use it.

You will have to experiment with the strenght to see what works for you, especially between models and depending on your other activated LORAs.