Using "sea legs" figuratively
Yes.
The Free Dictionary gives the figurative use:
sea legs
The ability to adjust to a new situation or difficult conditions, as in She's only spoken in public a few times; she hasn't found her sea legs yet. This expression was first recorded in 1712 and then referred to, as it still does, the ability to walk steadily on board ship, especially in rough seas. By the late 1800s it was being transferred to other challenging situations.