"Combat" in ASI refers to glorified steamrolling of tinies, who receive more damage and deal less damage
What matters is the size difference. Tinies fighting tinies will be the same as normal PvP, and giants may be crushed by giga-giants.
Scaled-up players (or monsters!) deal more damage to those smaller than them.
Beegs receive less damage the bigger they are.
Smols receive more damage the smaller they are.