Only embedding the embed as documented is supported.
You can use darkpopout=1 to force dark mode on the chat embeds, otherwise user preference should apply/be recalled.
You can’t override the server.
The sandbox option tells your site what to allow on the embedded site if your site has restrictions.
if you specify more permissions that Twitch requests in the docs, that dones’t make Twitch apply/allow those extra perms
So you add allow-storage-access-by-user-activation allow-scripts allow-same-origin allow-popups allow-popups-to-escape-sandbox allow-modals
if you add more Twitch doesn’t add more it will ignore.