I recently added a post (#6) to my journal regarding this topic:
https://www.babyandbump.com/dieting-weight-loss-fitness/315559-aliss-6-week-challenge-journal.html
It has a link to various exercises and a nutrition recommendation (neither works without the other!). In short, yes, it is possible. I know many women that have even better abs after having their baby.
One famous figure (bodybuilding) competitor is Jennifer Nicole Lee. Here is her before shot and after shot. Yes, that is post-baby in the "after".
It's a lot of work, an absolute lifestyle change. It's hard for most moms to justify putting the time and effort into it, which is why some people don't think it is actually possible. But it is (physically, at least).