I know this would vary depending on specific use cases but I want to know what the standard practices are. Let's say we have a darkmode option on our website and users can toggle it. And this change should be preserved. then I guess

1. if we require the users to log in and the changes should persist between different devices then we should use cookies to send the user settings and store it somewhere in the backend?
2. if we do not require the user to log in and we just want it to persist on this particular device then we can just store it in the localStorage? Are there any good articles or blog posts I can read on this topic? Also if we are using SSR and we decide to store it in localStorage. Does that mean the user might first see a wrong theme and then once the HTML gets rehydrated they can see the correct theme?