Primarily, Gomes is not 5'3. In a photo with Mata coming off the field and Gomes coming on, Mata (who is 5'7) stands but an inch taller than Gomes. At the least that should put Gomes at 5'5 - 5'6.
Secondarily, Gomes has a smaller bone frame than the likes of Foden and Bernardo, and therefore despite the height ranges being similar in comparison, Gomes will carry less weight than the aforementioned Foden and Bernardo.
But even then, perception isn't everything. Bulkier doesn't necessarily equate to stronger. I'm 5'6 and around 180lbs. I unabashedly train for lean muscle mass and to look bigger, and therefore I'm big for my height. In contrast, there's a couple of lads in my gym that are an inch or two shorter than me, weigh probably around 155 lbs (or less) and are visible smaller than me, yet their power and strength lifts exceed my own.
The point being that Gomes' goal is to get stronger and not necessarily bigger in appearance. It isn't a direct correlation.