Is there a roblox clothing template that fits R15 properly?

if you want clothes that genuinely bend with an R15 body, that's layered clothing, which is a 3D mesh rather than a flat template. that's a blender job and it has its own upload requirements, so it's a different hobby really, but it's the only proper fix for the elbow and knee seams.

There isn't a separate one. Classic shirts and pants use the same template on R6 and R15, the R15 body just splits each arm and leg into three parts, so the seams land at the elbows and knees. Designers work around it rather than fix it: keep logos, text and sharp lines away from those joint areas, and let stripes or patterns run continuously so the break doesn't show. Put the shirt on an R15 dummy in Studio and check it in a walking pose before uploading, a front-facing preview hides most of the bending.