As of today, there is currently no easy configuration that you could to keep the sum of story points (calculated by summing all the story points in the child issues) for an epic to be updated throughout all the possible events and triggers that may cause the number to be incorrect.

For example, the example found here: https://www.atlassian.com/software/jira/automation-template-library/sum-up-story-points - only covers for when issues have their field value updated, not for when issues are deleted, moved, created, linked to epic or link removed from epic.

This suggestion is to properly have the option to have multiple triggers available and easily accessing their values for properly updating the sum of story points.

A possible workaround can be achieved by setting up two rules, one being the trigger and the other updating the epic SP with its child issues SP sum