What happens if a MacBook Pro with macOS Catalina is restarted with open applications?

Should we close open applications before restarting a MacBook Pro with macOS Catalina? Or is it okay to be lazy and restart it without closing them?

Most applications from Apple, and some others, will save state and restart properly. Some will cause a pop-up saying "Application XYZ has canceled logout; quit and try again." (Not exact words.) Then if you're on "autopilot." you close the lid and when you next open it, it's still there.

To clarify that last confusing statement: Several times, I order "shutdown but re-open apps" and came back later to find it had not shut down because some application had asked me to do something and that canceled shutdown.

LibreOffice will come back up saying documents need to be recovered (and any edits immediately before shutdown will be lost). GraphicConverter 10 comes up OK but sometimes fails to find the images it had open before. You'd have to experiment with others.

I've gotten to the point where I close everything but Finder windows, Safari, and TextEdit before I shut down.

The Resume Feature, as far as I know, should still take into effect if you have the "Reopen Windows When logging back in" option check-marked in the restart window. It's the feature that reopens all windows and apps that you had open in your last session before you logged out and restarted your computer. So, yes it should normally be safe to restart and have all that you had open before restarting, back up and open again as soon as you log back in.