What is the biggest size I can print a downloaded picture as a poster?

I want to gift my friend a poster of a picture that he loves. I found it and downloaded it. It says it has 3360 × 4940 pixels and 72 DPI.

What is the biggest size in which it would still look good on a wall? I was thinking something like 30x45 or 35x50 (cm). I was thinking of putting it in a partout frame. Is this possible?

I have no clue about any of this so I would really appreciate any help on this. Sorry if this is the wrong place to ask for help, please point me to the right sub if so.