punches above one's weight

To punch above one's weight is to compete or perform at a level beyond what one's size, resources, or status would suggest.

From boxing, where fighters are matched by weight class.

Someone punching above their weight succeeds against stronger opponents or in situations where they'd be expected to fail: For a small startup, they're punching well above their weight against industry giants.

Often describes romantic relationships where one partner seems to have "outkicked their coverage."