Nope the regular updates via the admin dashboard interface do not result in any downtime on the site. That only happens when you do the full rebuild from the command line.
One thing to keep in mind is occasionally updating will add some background jobs e.g. re-optimizing images which can affect performance temporarily. That does happen pretty rarely but that one re: images was just a couple months ago so something to be aware of if you haven’t updated in a while. Can’t hurt to wait to run the update at a non-peak time just in case.