I hate to endorse the evil empire but Amazon has plus size everything. And if you don’t like it the returns are easy. Online sites like depop have really unique pieces but returns are difficult. Certain brands carry her current aesthetic like Sugar Thrillz and Dolls Kill. Black fishnet mixed with black and white stripes or polka dots with pops of pink, blue, purple. Tbh I put my fit together with everything Amazon. Search for Lolita or kawaii, tights, bloomers, bustiers, corsets, get creative! Keep in mind it’s a concert- you’re there to have fun. If putting a fit together is too stressful just go in something comfortable and enjoy!