Trying to find some t-shirts with British flag

Indijkeee

Hello! I'm trying to find some t-shirts with British flag for g8f or g9, please help) I need something like this

barbult

This product has textures with the flag.  It requires https://www.daz3d.com/dforce-wet-and-dry-tops-for-genesis-9-8-and-81-female

 

Gordig

I think London Look is what the character is wearing in that promo.

CES3D

You could also use Layered Image Editor to print a Union Jack on your existing shirt.
It's easy if the shirt's UV map is a front view.