Trying to set up a new account

A new Apple ID?

See this:

Create an Apple ID using the App Store on your device

1. Open the App Store and tap the sign-in button .
2. Tap Create New Apple ID. If you don't see this option, make sure that you're signed out of iCloud.
3. Follow the onscreen steps to provide an email address, create a strong password, and set your device region. The email address that you provide will be your new Apple ID.*
4. Enter your credit card and billing information, then tap Next. You can also choose None. Learn what to do if None isn't showing or you can't select it. You won't be charged until you make a purchase. 
5. Confirm your phone number. This can help to verify your identity and recover your account if needed. Tap Next.
6. Check your email for a verification email from Apple and verify your email address.

After you verify your email address, you can use your Apple ID to sign in to the iTunes Store, App Store, and other Apple services such as iCloud.

Also, If you're really having an iPhone SE I would recommend not staying on iOS 12 but to upgrade to iOS 15. If you have an iPhone 6/6plus you cannot update further then iOS 12.5.6 due to hardware limitations