I am unable to sign into my iPhone with Apple ID

If you can't connect or sign in to iCloud or your account, Apple has a list of things you can try in the document If you can't connect or sign in to iCloud - Apple Support

Is the iCloud server working? --> Apple - Support - System Status

If you are using a VPN, try turning it off and see if you can then log in. E.g., AppStore - Apple Community

If you are trying to use a service from outside your Home Country it may not be available. Apple Media Services Terms and Conditions - Legal - Apple Media Services - Apple

- A. ”Our Services are available for your use in your country of residence (“Home Country”).

And: "Certain Services and Content available to you in your Home Country may not be available to you when traveling outside of your Home Country."

If an item is greyed out or restricted, see this support article —> Use Screen Time on your iPhone or iPad - Apple Support

For more assistance try the iCloud Support web site --> iCloud - Official Apple Support

If you still have problems try official Apple Support. Click here --> Choose your country or region - Official Apple Support Select your country, then a product. If you don't see one that handles your issue then keep experimenting with selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.

or:

Contact Apple for support and service --> "See a list of Apple phone numbers around the world."

Click here --> Contact Apple for support and service - Apple Support

What is happening when you’re trying to sign in? What is the exact error that you’re facing?