Yes and no. The so-called vacuum pose is good for ab and stomach control. You wanna for it for more than 15 seconds thought - that's barely worth the effort. I can do that and I'm not slim lol.
Try 45-60 seconds 3 x at a go.
Key is also not eating large meals. Smaller, if more frequent meals, are better.
There's a LOT of BS online about how insulin and GH have caused guts to grow but, as I asked recently, if that was true there'd be a lot of ex-pros with big guts and when most retired their stomachs shrunk.
If you are broad in the hips then your waist will still be wide but flat.