As others have said, you will need to switch other counts individually. Even if tools existed, would you want a 3rd party to know all the accounts you have?

That being said, you don’t need to do it all immediately (as others also mentioned). What I did was change emails for my most important services and things I use often and made sure they were working (banks, gog, online shops etc.). Then I export all the emails I had in other accounts and imported into proton. I took that opportunity to sort things a bit but not really necessary. Then I set up forwarding from my other email accounts. I did this over my first few weeks with proton and now, if I happen to need an old account or notice emails are getting forwarded, I will switch those things. I can also see this in proton pass and if I notice an account has a sign in with an old email I’ll try change it to the new on before doing stuff with it.

If you take it easy and just focus on getting forwarding working and ensuring your most use stuff is switched over then it’s not too much of a ball ache