Created a new Apple ID on my phone and now I can’t sign out of my iPad to sign in with the new Apple ID

Creating a new Apple Account is unrelated to the Apple Account holding Activation Lock.

Activation Lock is int eded as a theft deterrent, and is intentionally difficult to bypass.

You will either need the password to the Apple Account holding the lock, or the person holding the lock can remove it remotely. If you don’t have the Apple Account credentials and cannot use Account Recovery to regain access to your Apple Account, then you will need proof of ownership sufficient to convince Apple. That’s usually an original purchase receipt from Apple or an Apple authorized reseller.

You need the password to the account signed into the iPad in order to remove the account. Do you recognize the account that is signed into the iPad, or is it someone else's?