I do not believe Word's Find feature can find these numbers because they are not really there. They are not "text." In the same vein, you cannot edit them manually.

You can use GoTo (Ctrl+G) to go to a particular heading.

Generating a Table of Contents from your headings will give you hyperlinks to them.

Why use Microsoft Word’s built-in heading styles? by Shauna Kelly
How to create numbered headings or outline numbering in Ribbon Versions of Word by Shauna Kelly
Generating a Table of Contents - Complex Documents