Hello Ryannquigley,
Being able to manage notification settings for the apps on your iPhone is important and you've come to a great place for help! It looks as though you're going in to Settings > Notifications, and not seeing Mail in the list of applications, and we're glad to see you came from the related article: Customize your Mail notifications on your iPhone, iPad, or iPod touch
Since noticing this issue, have you verified the email address is signed via Settings > Mail > Accounts and confirmed that Mail for that account has a green toggle next to it? If so, have you confirmed that Content & Privacy Restrictions isn't enabled in Settings > Screen Time > Content & Privacy Restrictions? If you see a green toggle next to Content & Privacy Restrictions, tap the toggle to disable that feature, then return to Settings > Notifications to see if Mail appears.
If that setting is already disabled or Mail doesn't appear, you'll want to confirm that the latest iOS version is installed. You can find the steps for updating iOS in the following article.
Update your iPhone, iPad, or iPod touch
Let us know how that goes!