Save compressed texture on disk

Hi. just wanted to know if its possible to save the ue5/ue4 compressed and resized texture as main uasset file (I mean the texture that unreal saves as uasset) to save disk space in a UE project? currently i made some textures in sbs designer and they are 10mb each when i compressed them in ue5 they become 400kb but when i checked the content folder size. it was 10 mb again.