StartMail supports a form of this called as "aliases" with the StartMail domain.

https://www.startmail.com/

(Disclosure: I work at StartMail.)

I do this with ProtonMail. I have it set on a subdomain, though: my regular email is email@example.com, while my account email is hackernews@email.example.com. This avoids the spam sent to asdf@everydomain.

Fastmail, can't recall if assuming you want to achieve something like name+tag@domain it would be name@tag.domain or tag@name.domain (IIRC the latter)

You can do this with Fastmail by going to Settings => Domains => Edit => Routing.