airpods pro not connecting

An iPhone 6 is not directly compatibel with AirPods Pro.

AirPods Pro Compatibility:

iPhone 12 Pro

iPhone 12 Pro Max

iPhone 12 mini

iPhone 12

iPhone 11 Pro

iPhone 11 Pro Max

iPhone 11

iPhone SE (2nd generation)

iPhone XS

iPhone XS Max

iPhone XR

iPhone X

iPhone 8

iPhone 8 Plus

iPhone 7

iPhone 7 Plus

iPhone 6s

iPhone 6s Plus

iPhone SE (1st generation)

Note:

AirPods Pro can be used as Bluetooth headphones with Apple devices using earlier software

and with non-Apple devices, but functionality is limited.