There currently is no option to change character size.
According to the Marvel Multiverse Core Rule Book p.39 & p.73 character size can change Speeds, Token Sizes, Melee & Agility defense scores as well as Melee damage multipliers.
Example:
A sentinel is gigantic sized and rank 4.
The melee damage multiplier should be 8 (rank 4 + size modifier 4) unless it were to have another power that provides an even greater damage modifier.
The melee and agility defense scores should be modified by -3.
The speeds should be multiplied by the size multiplier of 20
There currently is no option to change character size.
According to the Marvel Multiverse Core Rule Book p.39 & p.73 character size can change Speeds, Token Sizes, Melee & Agility defense scores as well as Melee damage multipliers.
Example: A sentinel is gigantic sized and rank 4.