Not sure what you think "declaring residency" means. If you lived in a state in 2024 and earned income in that state, you are subject to paying state tax there if that state has a state income tax. When you prepare your federal return, you need to use the mailing address where you want the IRS to mail you a letter or a check. When you enter your information into MY INFO you will need to show that you earned income in the state you lived in. If you moved sometime during the year, you might need to prepare part-year returns for the "old" site and the "new " state.
MOVED OR NEED TO FILE PART-YEAR STATE
https://ttlc.intuit.com/questions/1901560-how-do-i-file-if-i-moved-to-a-different-state-last-year
For the federal tax, it does not matter what state you live in or file as a resident in.
For the state tax, you would be considered a full-year or part-year resident in the state you lived in during the year if while you were there you did not intend to return to the state you moved from. It is less important that you "declare residency" than what your intention regarding staying there versus returning to the state you moved from was.
So if you left one state for another and did not intend to return to live in the former state, you would file as a resident, part or full year, in the state you moved to.