There’s a lot of flexibility in how you can manage your updates in Sync. You have the ability to update everything at once for every site, or just make one single update on one site.
From the Sync dashboard you can view an overview of pending updates for all Synced sites.
Click View Updates in any section to see the corresponding available updates.
You can view available from the site's Overview.
Clicking the Updates button on the left sidebar will show available updates.