u/BasilApprehensive466

I will be leaving RTX soon and was wondering if anyone had advice on what I should save/download or what steps I should take before leaving. Planning on saving W2 and paycheck info, but are there other things I should save? Does anyone have any advice on what to do with 401k and HSA? My new job has both options, but can I leave my accounts where they are or do I have to move them?

This is my first job switch so I have no experience in this. TIA!