What is the best way to help a new player join a higher level party?

Having spent lockdown watching us play from the sidelines, and having played in one shots of a couple of different systems. One of our party’s partners would like to join the d&d campaign I am running. As a DM I have no issues with this, she gets the game and has been reading the rules and the party of 4 could easily accept a 5th member.

However I am now wondering how best to create her character with her. In the past when a party member has joined a campaign I am running they are not new to role playing, this is not their first campaign and so they have already experienced taking a level 1 character through the ranks, therefore starting them at the same or a slightly lower level then the party is not an issue, they have played enough to be able to quickly pick up all the extra skills and abilities a sudden jump gives them, the magic items I allow them to start with at that level are not something more to learn to use. The party are all roughly levels 8-10 so I can’t bring her on as a level 1 character.

What is the best way to help her not feel overwhelmed by everything while allowing her to jump in with a more powerful character then most starT with. She hasn’t yet told me her race or class, we are planning an evening together to flesh all that out soon and I would like to go in prepared with some tips to help her get the most out of this and not spend the first few sessions feeling lost as she tries to remember everything her character can do.