w-2s are available from the Social Security Admin for a fee. 2010-2024 are avaialble and you get complete copies. the IRS only has Federal info (not state if needed) going back to 2018 (7 years). you can request transcripts using IRS form 4506-T (send POA with it)
https://www.irs.gov/individuals/get-transcript
as for tax info other than w-2s prior to 2018, sorry, in theory, the IRS no longer has copies.
Form 8821 doesn’t authorize your designee to speak on your behalf; to execute a request to allow disclosure of return or return information to another third party; to advocate your position regarding federal tax laws; to execute waivers, consents, closing agreements; or represent you in any other manner before the IRS. Use Form 2848, Power of Attorney and Declaration of Representative, to authorize an individual to represent you before the IRS. The designee may not substitute another party as your authorized designee.
form 2848 see if you are a qualified family member item f in Part II
