Add eSIM option is missing on my iPhone XR

First, what is the model number of the XR. iPhones made for use in China, Macao, Hong Kong or Singapore do not have eSIM support.

If your iPhone is not any of these, go to Settings, tap on Cellular, scroll down you should see Add eSIM in blue text, just below Delete eSIM in red, and just above Cellular data.

if you have a dual-SIM iPhone XR (with model numbers A2107 and A2108 for China mainland), you don’t have and can’t add eSIM.

Identify your iPhone model - Apple Support