25+ according to the multiplayer options (if they remain the same of course)
Unfortunately, as far as I know, dnd 5e does not have levels past 20 in raw. 4e, and other editions did though and had epic levels as past 20 is where characters as a party can start to contend with strong and godly beings in those editions. Around 17-20 in 5e is where you reach that kind of pinnacle if you did not multiclass.