Note that a dashboard upgrade is not always available, and when it is available, it’s not always successful. You might find you need to do a command-line upgrade after all, so make sure you have the time to do that.
With a command-line upgrade, you can expect 5 to 10 mins of downtime, maybe more, depending on how big your data is and how fast your host.
There is an advanced setup which delivers zero downtime, or very short downtime - you’ll need expertise! I haven’t tried this.
Move from standalone container to separate web and data containers