Scale hitbox and visual size independently

When using Pehkui with character model editors like Customizable Player Models and Figura, playermodel creators have to make their models smaller or larger than they should otherwise be in order to compensate for Pehkui changing the size of the model (especially in the case of non-standard width).

Is it at all possible to add commands that change the player's hitbox or mechanical size without altering the dimensions of their visual playermodel?

whoops wrong github i meant this for Pehkui