Pick a random map when you want a new layout

Ashes of the Singularity II supports procedural maps in both offline skirmish and online multiplayer, according to the developer FAQ. Choose the random-map option available in your match setup when you want to practice adapting to unfamiliar terrain. Choose a prebuilt map when you want to repeat an opening and compare what changed in your decisions.

Scout the map before committing your opening

On a generated battlefield, spend your first scouting pass locating practical ways out of your starting area. Look for routes that let you move between nearby positions and for terrain that could force armies through the same narrow approach. Choose an opening based on the layout you've been given. Save a second expansion option in case an opponent claims your first choice.

Decide which kind of practice you want

Practice goalMap choice
Get better at reading unfamiliar startsUse a procedural map and review your first scouting decisions afterward.
Refine a particular openingUse the same prebuilt map and repeat the opening under similar conditions.
Play with friends onlineAgree on whether you want a fresh layout or a familiar battlefield before setting up the match.

The official Ashes II FAQ confirms both generated and prebuilt battlefields. The documented support covers offline skirmish and online multiplayer.

FAQ

Are procedural maps available offline?

Yes. The developer FAQ names offline skirmish as one supported mode.

Can I use a random map in online multiplayer?

Yes. The same FAQ also confirms support for online multiplayer.

Are random maps the same as a map editor?

The FAQ describes random generation separately from a map editor. It did not announce an editor for launch.