Ruthlessness is the key. Nothing gets to sit in my inbox for more than a few hours. I go through it first thing, lunch time and at the end of the day. Other than that I work in other communication channels such as slack, which are far better for team comms.
I agree with pp, take everything in your in box up until say, Monday this week, and shove it in a folder. You can find it later if you need it.
Then, deal with what you have left.
Go through what you have and set up some auto filters based on the contents.
Meeting invites can be auto filtered, depending on how you work. I have my calendar open all day because I rely on it, so i see meeting invites appear directly in there. As a result, all my meeting invite emails are automatically filed. I go through my calendar a couple of times a day and accept/ decline appointments.
I get email notifications for stuff for which I also get notifications for elsewhere, such as on our helpdesk system, where they show up on my dashboard. They get auto filed too.
My personal stuff, annual leave approvals etc, all get auto filed and then deleted. It's all on our hr online record so keeping it is a duplication.
Junk mail gets blocked, unsubscribed and deleted, automatically where possible, if not I do it manually.
Any client questions get forwarded to a central help desk. I do that as soon as I see the email, then file it under done.
Anything for action that I can't do there and then, I add as a task to my calendar, and then I get reminded to deal with it, with a link to the email.
Anything where I'm in it because I'm copied in for info, gets read and filed.
Anything irrelevant to me gets binned.
I get maybe 3-4 emails a day which genuinely need action, and probably a hundred to two hundred plus a day which can be completely ignored.