How to use call forwarding on my Google smartphone

Note:

With call forwarding, you can direct some or all of your incoming calls to another phone number. You can use call forwarding at a pay-per-use charge of $0.25/minute, or you can subscribe to the call forwarding add-on for a monthly fee.

Google Pixel, Pixel XL, Pixel 2 XL, Pixel 2, Pixel 3 XL, Pixel 3, Pixel 3a, Pixel 3a XL, Pixel 4, Pixel 4 XL, Pixel 4a, Pixel 5.