Depending on the website the code can be placed on the site using various plugins or widget areas.
If your client runs a WordPress site, the code can be placed inside the Body, Header or Footer of the website. You can use the following plugins:
Elementor Plugin: https://themes.artbees.net/docs/adding-html-codes-directly-in-page-using-elementor/
Headers and Footers Plugin: https://wordpress.org/plugins/insert-headers-and-footers/
Add Embed Code: https://support.wix.com/en/article/embedding-custom-code-to-your-site
4. Add
Everyone would have a different site / Plugins and that's why we recommend sending the code to the Webmaster. Basically, the code should be placed either in the Header, Body or the Footer of HTML. There are also options for adding an Embed code to the Custom HTML / Widget area on sites that are not run by WordPress. Because there are so many different setups, we cannot put together one solution that would fit all. But if you let me know what site you have I can give you some ideas.