The focus mode is the best for all levels
Best mode to play as a newer player


Try 10 | 5 it's the best for thinking not too fast and not too slow. Also do puzzle rush survival (it's great).
I don't know what you mean by 'mode', I think you're talking about time control but I also think you are trying to ask us what the best chess variant is (Crazyhouse which I have discovered recently). Umm... do you mean what the best chess site is? if you are asking for that I recommend uhh- Lichess.org because it's good for beginners that just likes playing, Chess.com is for people that wants a larger community and also better looking GUI.
@1
Best is 15|10. It is the official rapid time control like for the World Championship.
Thanks to the increment you always have time to win a won position or draw a drawn position.

Im new, i learned to play over 35yrs ago, i play now to to help with Mindfulness... so im free a lot for games if you want to practise

Openings Resources for Beginners and Beyond…
https://www.chess.com/blog/RussBell/openings-resources-for-beginners-and-beyond
Looking for recommendations on what to play if I am newer and trying to improve