It’s great to detect security leaks, but I can also just delete the address and then any email to it will bounce. This usually gets you off their list anyway after a hard bounce.
If a company leaks your email or stops respecting your choice about how they email you, you can just blackhole that username+aliases@gmail.com straight to trash.
If a service refuses to allow you to use + in your email address you can use the period “hack” (I call it a hack, cause iirc it was meant as impersonation protectionand not meant to be used this way). On gmail your username can basically have as many or as few periods in it as you like. So using the Foo.Bar@gmail example foobar@ f.oobar@ fo.obar@ Fooba.r@ etc etc etc all work. You will just have to keep track on which username&period combo you used on X service yourself.
I think there are some services that lets you set up forwarders, and even some domain registrars will give you this for free or a small fee (although I guess the script part might be something you’ll have to figure out)
I have other reasons for having my own server (more mailboxes, domains, vendor lockin protection, own backups etc)