>>9484991Just look up 1/6 Barbie furniture and 1/6th action figure stuff. Barbie stuff is honestly really under scaled so they usually end up being the perfect size for the slightly shorter Bratz dolls. Wish and Aliexpress has a bunch of knock off Barbie accessories that are perfect for your needs.
The Ikea Huset set is actually a perfect scale for Bratz if you want an in scale shelving unit and couch. It's under scaled for Barbie but I heavily recommend this as the basis of your diorama and building up on it with doll accessories and stuff. I actually bought two sets since the pieces are really nice to stack together.
https://www.ikea.com/au/en/p/huset-dolls-furniture-living-room-30235511/ 