Brazil and Argentina are favorites in almost every edition to win the title, but don't forget that Uruguay also deserves a chance in this edition. Other national teams seem less reliable than the 3 above, but sometimes Chile is also good.
Interestingly, Messi and several other older Argentina players will still take part in this year's edition. They're not done yet and are still the favorites, but I'm not so sure I see Argentina retaining their title. Brazil is definitely ahead of Argentina in my opinion, but I think both deserve to be in the final.
Copa América history shows that Argentina is a most successful team in Copa América with 15 titles and 14 runner-up times. They have same total titles like Uruguay but Uruguay has only 6 runner-up times. Brazil is a third most successful team with 9 titles and 12 runner-up times.
It will make many people surprised that Brazil has considerable less Copa América titles than Argentina and Uruguay. In this Copa América, Argentina will be a best candidate for the trophy after winning World Cup 2022.