How to make a multi sided token with different sized token?

One of my players can grow from medium to large size, is there a way i can have him do it for himself without me increasing his size? Also can i simply do this with tokens using the multi sided function?

Unfortunately, no. It can be done with a Mod script quite easily (which requires the game creator to have a Pro subscription).  If you want a non-Pro alternative, you could have multiple characters with different sized default tokens that the player controls, and each one could have a rollable token for those sized tokens. The player would have to pull out the token from the Journal and delete the previous one.