Welcome!
In many cases you wouldn’t impose restrictions, especially if you have full control of the services that are running in the container. For example, if you are running nginx in a container, the default settings limit the processing power. Also, you wouldn’t need to worry for disk space unless you allow file uploads.
The reason why those restrictions are tricky, is if you do not select them properly, you may starve the services when they are just a bit under heavier load.
Having said that, this discussion forum provides support for Incus, which is a continuation of LXD. I’ll show you how to do those limits with Incus.
You would create a separate project and put those limits into that project, including limits.disk.