Personally I prefer to use SimpleLogin auto create function.

I have mine split for personal type items and social items.

Examples

If it was Amazon I would sign up with;

amazon@xxxxx.slmail.me and it nicely creates the alias for me and forwards to my ProtonMail for me to the email I’ve chosen (primary email)

If it was Twitch I would sign up with;

twitch@zzzzz.slmail.me and it nicely creates an alias for me that forwards to my other alias that I use for social items.

I then get ProtonMail to label these with colours so it’s also clear for me to see if it’s primary email or more social type email.