This is very easy. If you have built a custom post type and want to create a custom archive page for that custom post type then you have to copy the default archive.php file in your active theme. I would recommend using a child theme. Then rename that new file like this archive-{custom-post-type}.php
.
Follow the below steps:
- Copy the default archive.php file in the active theme folder
- Rename the file name like
archive-{custom-post-type}.php
- Then save it.
Your custom archive page created for the custom post type.