2021-11-20T16:18:00Z updated. This page is SPECULATION until after 2021-11-21T23:00:00Z when we get to activate the game and try this info ourselves.
Also it will take some hours? days? before first user made terrains are released, so this page remains empty placeholder until that time when we get first terrain release.
Maps / Terrains listed below are 8.1 kilometer (km) size, which are quite large.
Maps / Terrains listed below are 4 Kilometer (km) size, this is quite small terrain but people in FS19 and earlier games have most often done this sized terrain when they want larger, even in FS19 this seems to be very common size because people have not yet learned to fully utilize latest developments in terrain editing.
Maps / Terrains listed below are 2 Kilometer (km) size, same as original games Erlengrat, Haut-Beyleron and Elmcreek, meaning... small