If you work in a building that acts like a giant cell-blocking cage, enabling WiFi calling can help you make and receive phone calls when in areas where Verizon/ATT/Sprint can't touch.
Because there are so many different models and versions of Android, it's hard to provide definitive steps, but the steps below should be very close to accurate depending on your model. If this doesn't work for you, try Googling your phone model and the phrase "enable wifi calling." For example, if you have a Galaxy Note 20, Googling "Galaxy Note 20 enable wifi calling" gives tons of results:
General Steps to Take:
Open your settings app
Click on the Search icon and search for "WiFi calling"
Tap on the result, and it should send you to a menu that has the WiFi calling feature:
Tap on the WiFi Calling option and set the toggle to on: