Onn wireless keyboard

Hi gwstafford35,

Welcome to Apple Support Communities. We understand that you're having an issue with pairing a 3rd party keyboard with your iPhone 12 Pro Max. We'd like to help.

According to this resource, it may be possible to make this connection between your onn. Wireless Keyboard and your iPhone: Pair a third-party Bluetooth accessory with your iPhone, iPad, or iPod touch - Apple Support

Pair your device with a Bluetooth accessory 

1. On your device, go to Settings > Bluetooth and turn on Bluetooth. Stay on this screen until you complete the steps to pair your accessory. 

2. Place your accessory in discovery mode and wait for it to appear on your device. If you don't see it or aren't sure how to make it discoverable, check the instructions that came with your accessory or contact the manufacturer.

3. To pair, tap your accessory name when it appears onscreen. You might need to enter the PIN or passcode. If you aren't sure what your PIN or passcode is, check the documentation for your accessory.

After you pair your accessory, you can use it with your device. To pair multiple Bluetooth accessories, repeat these steps. You can also learn how to switch audio sources for your device.

If that doesn't resolve your issue, you may want to reach out to onn. for additional support

Hope that helps!