You can use the simulated chat preview or your live chat from Twitch to configure your chat overlay.
After configuring everything you can copy the overlay URL and use it as browser source in OBS, StreamLabs, etc.
%20{%20:root%20{%20filter:%20none;%20}%20}%20@media%20(prefers-color-scheme:%20dark)%20{%20:root%20{%20filter:%20none;%20}%20}%20%3c/style%3e%3c/svg%3e)