Person Thats a bug at the moment.
Normally it would be permanent.
https://rpginabox.com/forum/d/345-set-entity-model-does-not-persist-through-load-map
Both set_enttity_model and change_player are designed to be permanent when used....but right now, load map is unsetting the model and needs fixing.
The issue is strictly just tied to the model.
The "changed" player settings are still applied, even after a map load.
You will still have the new stats, inventory, equipment etc.
The only thing that for some reason gets put back when you load a map, is the player's model.
Hence why it needs looking at why it's doing that and fixing.
There is a fix that you as a designer can do and I will put a guide together to show how to workaround this issue in the meantime until it's officially fixed.
With this workaround, change player WILL work, and be permanent like it's supposed to be.
https://rpginabox.com/forum/d/770-workaround-load-map-resetting-player-model