Examples of the caldera_forms_submission_url filter. See: https://calderaforms.com/doc/caldera_forms_submission_url/

caldera_forms_submission_url-alt.php

<?php
add_filter( 'caldera_forms_submission_url', function( $url, $form_id ){
    if( 'CF582e6cf914f03' == $form_id ){
        $url = 'https://somesite.com/api';
    }
    
    return $url;
    
}, 25, 2 );

caldera_forms_submission_url-ssl.php

<?php
add_filter( 'caldera_forms_submission_url', function( $url, $form_id ){
    if( 'CF582e6cf914f03' == $form_id ){
        $url = set_url_scheme( $url, 'https' );
    }
    
    return $url;
    
}, 25, 2 );