There's not any free of charge addon for setting up Google Tag Manager in PrestaShop besides buying a compensated addon. Prestashop also doesn’t give usage of Web page code so we can easily add Tag Manager code but there is still an alternate way by straight modifying the web site https://addons.prestashop.com/pt/seo-referenciamento-natural/30904-tags-automaticas-hreflang-e-tags-canonicas-seo.html