How exactly does Sync Settings for Windows devices work?

My situation is that I only have the one device..a laptop. I only use a Microsoft Account and dont wish to set up a Local Account at all, so when clean installing the OS, as soon as Windows set up has completed, the first thing I do before making any changes is to go into Settings/Account/Sync Settings and turn off the Sync toggle. I have always thought that this ensures that no personal settings are saved in the cloud. Is my thinking correct here ..OR.. Do settings such as the WiFi network password and Desktop wallpaper theme get synced to the cloud automatically anyway because Windows turns on Syncing by default and these settings will be synced before I get the chance to turn off the Sync toggle.
If so..Do you guys just leave the Sync toggle On and not worry about it..even if you only have one Windows device signed in with a Microsoft Account?

M$ collects data and link to your M$ account to offer you something you may want to buy. It is how they make money.
If you want privacy you should set your account to local.
Why do you need or want to use a Microsoft Account?