I have these functions in the plugin class that accesses templates, or break them out into simple functions if I'm using a namespace

plugin-template-functions.php

<?php

    /**
    * load template from theme or plugin
    * @param string $template name of template to load
    * @param array $templateData data to make available to templates
    */
    public function loadTemplate($template, $templateData = []) {
        extract($templateData);

        $templatePath = $this->locateTemplate($template);

        if (!is_readable($templatePath)) {
            echo esc_html(sprintf(__('template not found or unreadable: %s', 'example-plugin'), $template));
            return;
        }

        require $templatePath;
    }

    /**
    * locate template in either theme or plugin
    * @param string $template name of template to load
    * @return string
    */
    protected function locateTemplate($template) {
        // accommodate both template names already ending with .php and names that don't
        if (substr($template, -4, 4) !== '.php') {
            $template .= '.php';
        }

        $templatePath = locate_template("plugins/example-plugin/$template");

        if (!$templatePath) {
            $templatePath = EXAMPLE_PLUGIN_ROOT . "templates/$template";
        }

        return $templatePath;
    }