ACF custom required field message

functions.php

function bbdfy_acf_require_custom_message( $field ) {
	acf_render_field_setting(
		$field,
		array(
			'label'        => __( 'Custom Error Message', 'acf' ),
			'instructions' => __( 'Error Message to display when feidls is require and not submitted.', 'acf' ),
			'type'         => 'textarea',
			'name'         => 'custom_error_message',
			'rows'         => 5,
		),
		true
	);
}
add_action( 'acf/render_field_settings', 'bbdfy_acf_require_custom_message', 100, 1 );


function bbdfy_acf_require_custom_message_display( $valid, $value, $field, $input ) {
	if ( ! empty( $field['required'] ) && ! empty( $field['custom_error_message'] ) && empty( $valid ) ) {
		$valid = $field['custom_error_message'];
	}

	return $valid;
}
add_action( 'acf/validate_value', 'bbdfy_acf_require_custom_message_display', 100, 4 );