You'll most commonly call end points server-side in field default functions or in form variables. Calling end points as pages load, or once they are submitted, is the safe, secure way to interact with the platform and pass data around.
This two page form has a text input field on the first page. On page two the default function of a guidance text field passes the value of the text field to an end point which hashes the string and returns the result.
![Server-side End Point Call](/image/6295/Server-side-End-Point-Call/gi-responsive__100.png?lastModified=1664458620317)
The blockly above is using .utilServerAPIServerCall.