How to override seeded characteristics of a field when properties are unavailable

Summary:

We see that there is no option to change characteristics of the Number field in adding a new contact of family & emergency contact page

And by nature this field is Required. We want to make it optional. How can we do it? Is there any JavaScript or something we can use?

Content (please ensure you mask any confidential information):

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):