If you want to step out of a Family Sharing group, then you can do so (if you’re old enough, over 13 I think for most countries). You wouldn’t need to change accounts.
Leave Family Sharing - Apple Support
If you change the email for an existing account, then that will propagate to Family Sharing as well. Nothing is different but the name of the account. The account and all services tied to it stay the same (except email). Change your Apple ID - Apple Support
If you create a fresh new account, then you can’t use the services that are tied to the former account. You would lose all those perks, including Family Sharing, subscriptions, past purchases, iCloud access. No-one would be notified automatically, unless you step out of the group. Depending on Sharing options, your device(s) can appear offline when registered with a new account. How to create a new Apple ID - Apple Support.
Switching between accounts is a hassle, as Apple ID accounts are tied to just about all services, and iPhone is intended as a single account device. I would advise to only use a new account if you intend to never return to the former.