In order to upgrade the stats of your NFT, you would need to play the game and earn XP. To upgrade each stat, a certain amount of XP is required. With each upgrade, your character potential is also increased.
We have 6 levels of Character Potential. Each level of Potential comes with 12 sub-levels of its own.
It is possible to upgrade your NFTs right now, and max upgrades allow you to upgrade up to 2 out of 6 levels of Potential. No XP is needed for this, but once Phase 1 launches, you will need XP to upgrade each stat.
After the launch of Phase 1, the ones with maximum upgrades will start at a different XP and Character Potential level than the ones with zero upgrades.