Hello and welcome to syncthing,
this can certainly be done, but I think you should make an exception for a few folders, most notably the .config/syncthing/index* folder.
There might be a few other files and folders that can cause trouble, e.g. your browser’s history database.
So it kind of depends on what you want - if you just want to sync your Pictures and Documents folder, then set up syncthing in such a way, that all hidden folders are being ignored (i.e. all folders starting with a dot)
If you want to sync all your settings to just have a backup - other tools might be a better choice.
If you want to even have the same settings on more than one machine - I am afraid you’ll probably be in for some trouble, especially if these machines run at the same time.
But if it is just your Documents you want to sync - then go ahead and use syncthing, it’ll do the job nicely!