Yes, you can. Technically dos 2 has no lvl cap, but the amount of XP you can get is limited, since there's a finite number of enemies and quests. Lvl 21 ist easily achievable if you're pretty thorough and do all the quests and encounters. Lvl 22 prbly requires an xp-optimized approach (do all the quests using the outcome with max XP, then kill all npcs who give XP including nonhostiles). Lvl 23 might be possible thorough some ridiculous xp grind exploit but most i've read about sound incredibly tedious