Microsoft is bringing back the option to block Media Autoplay on websites in the new Microsoft Edge browser via a flag in the Canary version.

Classic Microsoft Edge aka Edge Legacy offers a global and per-site setting to block automatic playback of videos on websites.
New Microsoft Edge currently offers ‘Allow’ and ‘Limit’ options in Media Autoplay Settings under Site Permissions. Previously, Microsoft also offered a Block setting which hasn’t worked and been pulled out.
Now through a new flag, Microsoft allows enabling Block option in autoplay Settings again, for that,
1. Launch latest Edge Canary
2. Visit edge://flags page
3. Search for ‘Show block option in autoplay Settings’

4. Select ‘Enabled’ from the dropdown and restart the browser.
5. Click on the ellipsis icon > Settings >
6. Site Permissions > Media Autoplay > “Control if audio and video play automatically on sites,” choose ‘Block’.
Apparently, the setting is not working now when enabled. You can check this by visiting a site like CNN where video be automatically played with sound, which shouldn’t be happening when you select that setting, but the ‘Limit’ setting is working.
Here is what the three media autoplay settings supposed to do when selected:
Allow is the default option that doesn’t apply autoplay restrictions on any website.
Block option stops videos from playing automatically on websites.
Depending on your engagement with the site in the past, the Limit option decides whether to block autoplay or not.
Related articles:
Chromium Edge removes Block option from Media Autoplay Settings
Microsoft rolls out redesigned Settings page and Video Autoplay blocking option to Chromium Edge
Microsoft Edge Chromium to limit Media Autoplay on websites