The unfortunate answer, at least right after launch, is no: Age of Empires 4 does not have a map editor or a scenario editor. The game launched without such a feature, much to the chagrin of many fans who tout it as one of the series’ best aspects.
Currently, you can create semi-custom skirmishes and multiplayer matches by choosing between the available civilizations, maps, and win conditions. And while you can also choose terrain types, your starting age, and how many resources are available in these modes, that’s about it.
You can’t create new maps or scenarios from scratch. There is an option to select “Crafted Maps” in the Map Setup menu in Skirmishes, but it cannot be chosen as of this writing. And there is a way to replay specific map layouts via seeds.
We’ve reached out to the team to see if there is new information regarding when or if a scenario editor or map editor may show up in Age of Empires 4. Some posts of Reddit and other forums posit that such a feature may arrive in 2022, when it appears mod support may also be integrated. But that’s unconfirmed as of now. Until then, stay tuned and check out our other Age of Empires 4 content.