Much like most things on Roblox, you will be making this yourself from scratch, so you'll need to design a t-shirt in an image and then upload it to Roblox. From there, just select it to wear and ...

Roblox discussed some other AI-based updates at RDC, too. One will let you create an avatar from an image and a text prompt, meaning it might be easier to make an avatar that looks more like yourself.