They absolutely can, but, especially with filler, I find injectors want to give you more.
The problem with lip filler, too, is that you can get an amount that just restores your lip volume as you age, but the first few days after the injections, your lips are very swollen, so you do get to experience what having bigger lips is like, even if that's not the result once they've settled.
When my lips were just done, they were very swollen, and men were actually going crazy for me in the street. It was very noticeable. The looks, the smiles, the eye contact. A really hot guy on a bike gestured positively to me. It was a total dick fiesta.
When I went back to my injector after ten days for my check up, she said she wanted to fill my lips a little more. Honestly, I was tempted to let her, and I can absolutely see how everyone ends up with massive lips.