Off course that's possible! I mean if you're >2meter >120kg bear mode, you're gunna have a hard time perhaps. But even me 195cm can feel that protected feel when being little spoon to my ~180 gf. But i can easilly be her big teddybear as well
Why would you think larger girls don't want to be dominant? If anything i'd expect the percentage of dominant to be larger among larger girls.
The reason the internetz like small girls is cuz they're betas who need a near kid-tier girl to still feel some dominance. Also small is comsidered cute and feminine. But that doesn't count as much if you're submissive. And a taller girl can be just as cute if she knows how to dress/style as such.