If I reset my console do I lose everything?

Your account is stored on the servers. You won't lose it by factory resetting. You just need to remember your login details so you can log into the same account on the new console.

As long as you weren't using your Xbox One completely offline, you won't lose anything. Sign into your account on your Series S and you can re-download any digital games you own without paying again, then as you launch games that you have progress on, your game saves will sync over via the Xbox Network, so you won't lose any game progress.

The only time you'd get in trouble is if A) you don't know the login details for your account and have no way of recovering it, or B) you were using your Xbox One completely offline all the time as then your saves wouldn't sync over to the new console.

I’d rather not remove everything. As I have a ton of saved data for every game that I’ve played. I’d hate to just lose it all by resetting it. I’ve pre-ordered Xbox consoles ever since the 360. And I have never encountered an issue like this. But the last thing I want to do is lose everything and time I’ve put into games by resetting the console

If you have your saved games backed up then you should be able to retrieve the data if that happens by going to backup and restore in the menus.

When you say restart, do you mean factory reset? If so, then you are correct you may be required to reinstall any installed games after the process is completed.