Landscaped Garden in Unreal

Bit of a noob question as I’m trying to figure this out. I want to create a landscaped garden. I’ve started in 3ds Max to design the assets (for example the patio slabs). What I’m anticipating as a problem in the future is how do I cut these patio slabs around a curve, as you would on a real live project, and how do I apply an effect of the couple of millimetres of grouting in-between the slabs?

Do I block out the garden using assets in Unreal, then to use edit functions in Unreal to subtract a curve using some sort of boolean operation, or would that all be done in 3ds Max, and I would use Unreal purely to populate the garden with these pre-edited assets?

I am going through the tutorials, I just know this is something which will trip me up in the near future.

Yes. Model everything on 3ds Max and throw it on unreal. Keep in mind that most of this process is back and forth.