Create custom endpoint to WordPress

create_custom_endpoint_to_wp.php

<?php

/**
 * Create custom RestAPI
 * @link http://wpplugins.local/wp-json/letsgo/v1/activatePlugin
 * @return void
 */
add_action( 'rest_api_init', function (): void {
	register_rest_route(
		'letsgo/v1', '/activatePlugin', [
			'methods'             => 'POST',
			'callback'            => 'activatePlugin',
			'permission_callback' => function () {
				return current_user_can( 'manage_options' );
			},
		]
	);
});

/**
 * Activate plugin
 * @param WP_REST_Request $request
 * @return WP_REST_Response
 */
function activatePlugin( WP_REST_Request $request ): WP_REST_Response {
	$plugin   = $request->get_param('plugin');
	$result   = processActivatePlugin( $plugin );
	$response = new WP_REST_Response( $result );
	
	if ( $result['success'] ) {
		$response->set_status( 200 );
	} else {
		$response->set_status( 400 );
	}
	
	return $response;
}

/**
 * Process activate plugin
 * @param string $plugin
 * @return array
 */
function processActivatePlugin( string $plugin ) : array {
	if ( empty( $plugin ) ) {
		return [
			'success' => false,
			'message' => esc_html__( 'Please enter a valid plugin slug', 'letsgo' ),
		];
	}
	
	$result = activate_plugin( $plugin );
	
	if ( is_wp_error( $result ) ) {
		return [
			'success' => false,
			'message' => $result->get_error_message(),
		];
	}
	
	return [
		'success' => true,
		'message' => sprintf( esc_html__( 'Plugin activated: %s', 'letsgo' ), $plugin ),
	];
}