Ask HN: How those websites play sound without user interaction first?

As far I know, there is no way to play any sound on a webpage if the user did not first interact with the page.

But Big compagny video like TikTok or Youtube achieve to do it. You can open a direct link to a TikTok video or a Youtube Short and it will play with sound without any click.

Does anyone know how they bypass the restriction ? Is it some kind of whitelist that the browsers implement ?