Unlock with Apple Watch is not showing up on my iPhone 11 Pro Max.

Make sure that you meet the minimum requirements to use Apple Watch to unlock your iPhone.

You'll need:

• Your iPhone (iPhone 11 Pro Max) with iOS 14.5 or newer. The latest version of iOS available is iOS 14.8.

Update your iPhone, iPad, or iPod touch - Apple Support

• Apple Watch Series 3 or newer with watchOS 7.4 or newer. The latest version of watchOS available is watchOS 7.6.2.

Identify your Apple Watch - Apple Support

Update your Apple Watch - Apple Support

For Unlock with Apple Watch to work, you'll also need:

• Wi-Fi and Bluetooth to be enabled. (You don't need to be connected to a Wi-Fi network)
• Your Watch needs to be paired to your iPhone

How to pair your Apple Watch with a new iPhone - Apple Support

• A mask or facial covering over part of your face
• Your Apple Watch needs a passcode set, and wrist detection turned on, and it needs to be on your wrist and unlocked.

Lock or unlock Apple Watch - Apple Support