Do the breast pumps for enlarging breasts actually work?

Perhaps. It may help decrease the fullness due to milk supply, making nursing a baby easier.
Maybe. You probably are breastfeeding your new baby, right? Breast enlargement or swelling is very common within the first few weeks of breastfeeding. Putting the baby to your breasts to nurse as often as possible will release your milk and reduce the pressure within your breast. Your baby will de a better job of emptying your milk compared to a breast pump which usually is not necessary.

Related Questions

Can I use normal breast pump to enlarge breasts?

Won't work. A breast pump is not going to result in breast enlargement. There are special pumps that can result in some increase in the size of the breasts.

What to do if I wanna enlarge my breasts. Is breast pump a safe option?

No. Enlarging breasts can be obtained by increasing the fat content via weight gain. There are very few women who would undertake that project willingly, and for that purpose. So, no a breast pump is not the way to go, but a plastic surgeon is.