Limit Uploaded Image Size

add_filter( 'wp_handle_upload', function ( $file ) {

	$max_width = 1920;

	$max_height = 1920;

	// Check if the file is an image.

	$mime_type = mime_content_type( $file['file'] );

	if ( strpos( $mime_type, 'image' ) === false ) {

		return $file;

	}

	// Get the image size.

	$image_size = getimagesize( $file['file'] );

	if ( ! $image_size ) {

		return $file;

	}

	// Check if the image is smaller than 1920px width or height.

	if ( $image_size[0] <= $max_width && $image_size[1] <= $max_height ) {

		return $file;

	}

	// Resize the image.

	$image_editor = wp_get_image_editor( $file['file'] );

	if ( is_wp_error( $image_editor ) ) {

		return $file;

	}

	$image_editor->resize( $max_width, $max_height );

	$image_editor->save( $file['file'] );

	return $file;

} );