Yes. Enable cheats (easter eggs) and press Ctrl + F10 when on the landview (the view where you click the flag and where you go to after winning a map).
You can find the "enable easter egg" option in the official launcher. This option requires you to use the launcher to start the game. Clicking keeperfx.exe directly does not enable cheats even if it's enabled in the launcher.
If you just want to play the last map, there's command line options to start the level directly: -campaign keeporig -level 20
You can find more info about these command line options here:
https://keeperfx.net/wiki/Command-Line-Options
You can also use Unearth to start a map directly from the map browser.