Output an ACF url field as html. Also allow for extra attributes.

acf_url_as_html.php

/**
 * Output ACF url field as HTML.
 *
 * Optionally add attributes to the link as an array.
 *
 * Example:
 *
 *    acf_format_link('cp_flex_tab_1', ['class' => 'btn btn-large', 'data-id' => 123]);
 *
 * Will render the field like so.
 * <a href="http://google.com" target="_blank" class="btn btn-large" data-id="123">Link text</a>
 *
 * @param string $field_name ACF field machine name.
 * @param array  $attributes A set of attributes to add to the link.
 *
 * @return boolean|string
 */
function acf_format_link( string $field_name, array $attributes = [] ) {
	$field = get_field( $field_name );

	// Return an empty string if field is empty.
	if ( ! $field ) {
		return false;
	}

	// Ensure basics.
	if ( ! isset( $field['title'] ) || empty( $field['title'] ) || ! isset( $field['url'] ) || empty( $field['url'] ) ) {
		return false;
	}

	// Generate attributes string.
	$attributes_output = '';
	if ( ! empty( $attributes ) ) {
		foreach ( $attributes as $attribute => &$data ) {
			$data               = implode( ' ', (array) $data );
			$attributes_output .= $attribute . '="' . esc_attr( $data ) . '" ';
		}
	}

	// Target.
	$target = '';
	if ( ! empty( $field['target'] ) ) {
		$target = "target='${field["target"]}'";
	}

	$output = "<a href='${field["url"]}' ${target} ${attributes_output}>${field["title"]}</a>";

	return $output;
}