Check which template loading in WordPress site.

check-current-template-path.php

<?php
/**
 * Check Which Template Loading
 *
 * @todo Change the `prefix_` from function name with your own prefix.
 * 
 * @since 1.0.0
 */
if( ! function_exists( 'prefix_check_loaded_template' ) ) :
	function prefix_check_loaded_template()
	{
		// This global variable contain the currently loaded template file path.
		global $template;
		?>
		<div class="loaded-page-template">
			<h3><?php _e( 'Template File:', 'prefix' ); ?></h3>
			<p><?php echo esc_url( $template ); ?></p>
		</div>

		<!-- SKIP the styling. Just for reference. -->
		<style type="text/css">
			.loaded-page-template {
			    position: fixed;
			    right: 0;
			    top: 0;
			    z-index: 99999999999;
			    background: #FFEB3B;
			    padding: 15px 20px;
			}
			.loaded-page-template h3 {
			    margin-bottom: 10px;
			    font-weight: bold;
			}
			.loaded-page-template p {
			    margin-bottom: 0;
			}
		</style>
		<?php
	}
	add_action('wp_head', 'prefix_check_loaded_template');
endif;