As a CubeCraft Bedrock expert, I'll answer some of your questions:
Does cubecraft have a level cap (max level)?
CubeCraft doesn't have a level cap or max level.
It seems like Cubecraft wouldn’t have a max level; they likely didn’t make the XP requirements for each level one at a time but rather made a system where it increments each level’s XP requirements by a certain amount after you level up.
As far as I'm aware, from level 1, you need 1000 XP (4 games of EggWars, 8 games of SkyWars) to level up to level 2. Every level increases the XP needed to level up by 200 (one game of EggWars), which means to level up to level 3, you need to earn 1200 XP after reaching level 2 (5 more games of EggWars, 10 more games of SkyWars).
A Other quastion who ist the Player with the highest lvl BC i think charxzz ist IT but i dont really know
As for the highest level player, on Bedrock, to my knowledge its Charxzz. Not sure who's the highest on Java as I don't play on that network, I think its Kloska but I can't confirm anything. Not counting John Coles (OG Management member) as shown in the photo above as that level is most likely modified.