Hey there @Plumick! The landscape system in Unreal isn’t meant to be modified at runtime, so runtime procedural mesh manipulation is off the table for the landscape system itself. Though there are mechanisms to paint holes, or even update the texture to apply the holes however this won’t change the collision. This older thread goes into detail a bit:
The alternatives boil down to faking it with a material, or if you actually need deformable terrain you will need to either dig into procedural meshes or custom voxels (or voxel plugin) as possible solutions based on need.
Disclaimer: One or more of these links are unaffiliated with Epic Games. Epic Games is not liable for anything that may occur outside of this Unreal Engine domain. Please exercise your best judgment when following links outside of the forums.