How can I unlock my iPhone 15 Pro without losing data?

If you mean the Passcode to unlock your device, then the phone will be reset and wiped, but you can still restore your data from an iCloud backup as long as you have one.

If you see a iPhone, iPad, or Apple Vision Pro unavailable message or Security Lockout screen - Apple Support

You can't, if you don't remember the passcode. If you do remember the correct passcode, wait until the time limit is up and enter the right passcode. But if you don't remember the code, you'll have to erase the phone using a computer, which will wipe it completely. Assuming you've been backing up your iPhone, you can then restore it from your most recent backup. If you haven't been backing up, some data may have been synced with iCloud, which you can restore. But if you're not backing up, nor syncing with iCloud your data will be gone.

See the following two links:

If you see a iPhone, iPad, or Apple Vision Pro unavailable message or Security Lockout screen - Apple Support

If you forgot your iPhone passcode or your iPhone is disabled - Apple Support