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If you previously have used iCloud and keychain, that's where most apps and browsers store them (you can scroll through keychain and check). If you don't use iCloud with keaychan, I don't know.
 
Weirdly when I updated to the 16 Pro Mac I was already logged in to everything as soon as the phone restored.
 
Do an encrypted backup on iTunes. Most passwords are saved but you need to re-do Face ID for phone unlock and it seems most financial institutions require that you enter your password to use Face ID for their site also.
 
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