No, it's entirely possible to cheat and be 1100, if you play most games without cheating:
www.reddit.com/r/chess/comments/8eoirz/im_done_with_lichess_flagged_for_no_reason_very/
www.reddit.com/r/chess/comments/8eoirz/im_done_with_lichess_flagged_for_no_reason_very/