Using The REST API How To Pull All Custom Posts?

The filter is dynamic, i.e. generated from rest_{$post_type}_query.

So for the post post type it’s rest_post_query and for the cpt post type it’s rest_cpt_query

Note that REST pagination is available:

https://example.com/wp-json/wp/v2/posts?per_page=100&page=1
https://example.com/wp-json/wp/v2/posts?per_page=100&page=2
...

The maximum of per_page is to reduce the risk of fatal errors if available resources are exceeded when too many items are fetched.