The WordPress REST API can be accessed with /wp-json/ and is the entry route that's appended to your site-based URLs. For example, you can see all the other available routes by pointing your browser to localhost:4000/wp-json/. You will see what endpoints are available in every route, as these can be either GET or POST endpoints. For example, the /wp-json/wp/v2/pages route has a GET endpoint for listing pages and a POST endpoint for creating a page. You can find out more about these default routes and endpoints at https://developer.wordpress.org/rest-api/reference/.
However, if you have custom post types and custom content fields, then you will need custom routes and endpoints. We can create custom versions of these by registering them with the register_rest_route function in the functions.php file, as follows:
add_action('rest_api_init', function () { , and then followed by the available endpoint
$args = [
'methods&apos...
