they should be scaled down, player-sized version of the primals. The models should even be simplified to reflect the difference in power between the actual primal and the summoner's version, i.e smaller horns/less glow on ifrit, smaller wings/less feathers on garuda, and smaller titan. I like to imagine a more human aesthetic to the primals to maybe reflect the summoners presence in their existence (not for leviathan since it is not anthropomorphic at all). Another way i think about it is the egi's are like the primal's "baby-spirits", where i wish they would be more adolescent/young adult in size/aesthetic relative to their storyline counterparts.

Young Ramuh? YES PLS