When you work with physics to simulate or analyze such as determining line of sight or where a projectile will go, you may need a surface with a mesh collider.
You can enable and disable the mesh collider by going to the Settings panel of the Modes Panel UI, and marking the Enable Mesh Colliders checkbox under the Physics tab accordingly. If you don't use the Modes Panel UI in your level to create the ArcGIS Map, you can enable this option by clicking the ArcGIS Map Component in the Outliner panel, and marking the Enable Mesh Colliders checkbox under the Settings section in the Details panel.
When it's enabled, a collider mesh will be generated for all layers in the ArcGIS Map. For using raycast with the mesh collider, see Unreal's documentation: Traces with Raycasts.