Songbirds lighter than a few coins fly nonstop across the Gulf of Mexico. Size is a bad predictor of what you can carry.

Capacity is not predictable from size. Something weighing almost nothing crosses hundreds of miles of open water without a single stop, which means the usual assumption about small things being limited is simply wrong. That same error gets made about people constantly: the quiet one, the youngest, the smallest in the squad.

If you have been counted out on appearance, do the work and let the performance answer it. Then check where you are making that assumption about somebody else, and give them the harder job.