I'm a 24 year old with mild asthma but no other chronic medical conditions. if i get infected with covid in europe (denmark or italy) in 2023, may my symptoms be just as mild as in a covid-controlled country or will they be more severe?

Are you vaccinated and boosted? If so you have the best protection. I would wear a mask when indoors in light of your increased risk. The only other protection is to delay or cancel your visit to countries with high covid risk.

Too many unknowns for a specific answer as of now. Getting vaccinated, wearing masks and avoiding crowds will give you the best chance to avoid infection, COVID and others.