<3 I don't see a point of wearing bra under a suit like that but still looks cool af
Bodysuits actually might need cups if they aren't solid, reinforced, or are fabricated with cups. Both of them look to be a decent size as well, so no cheats there.
On that note though, a tubetop is not a bra, and it is not a usually useful as breast support. In fact, it's usually the opposite. It's something many women wear to make their breasts appear bigger and bouncier. So it is a bit of an odd combo.