The E2E will help so long as you're sending email to other users of the same service, yeah. For most cases, it's probably not a huge upgrade from stored encrypted; the bulk of damage in email leaks would be from accumulated emails from the past.

The reason I don't recommend using it if you're super paranoid is because it'd be easy to mess up, and it comes with quite significant holes- e.g. subjects aren't E2E in Protonmail. Best to use a protocol designed for E2E from the ground up.

https://protonmail.com/support/knowledge-base/does-protonmai...