@jomo #Posteo supports 2 aliases for free, I think, otherwise 20 cents or so per alias. (Depends on how much aliases you want to use.) Mailbox.org also supports them AFAIK.
That + thing you mention is [one](https://jameshfisher.com/2018/04/07/the-dots-do-matter-how-to-scam-a-gmail-user.html) of the "great" features of GMail (actually taht one may indeed not be bad), but not supported by other mail providers. There you usually have to create aliases manually.
@jomo @lukas @rugk I just noticed that mailbox.org also supports plus aliases (that obviously don't count against the limit)
https://userforum.mailbox.org/knowledge-base/article/tipp-was-ist-ein-alias-und-wie-nutze-ich-diesen
@jomo Otherwise if you just want to use it for unimportant (spam/newsletter/…) mails you can alos use free services, which redirect your mail such as https://dnt.abine.com/ (look for "Mails" there).