Help with 3d topographic maps

Im trying to work with these stl files here

Realtively new to modeling and trying to use fusion 360 to modify the stl files to get what im wanting. What Im trying to do is rescale them, the originals are too thick and want only 1" deep and reduce the complexity. Wanting more elevation lines and something closer to this:

Not sure how to go about this, all the info I can find online skips over a lot of the steps. Any help finding a tutorial or pointing me in the right direction would be helpful. thanks

Evan and Katelyn - two vloggers who produce some great Maker content (https://evanandkatelyn.com/) have actually done exactly this.

I really mean exactly: that picture is from their site, albeit on someone else’s Thingverse (which is lame).

If you watch that video, they go into extensive detail.

They also have a lovely tutorial on Fusion 360 basics with the x-carve/Carvey.

They do a great job overall with that CAM tutorial, but they neglect to mention setting an appropriate roughing step size or optimal load… Broke my first bit trying to follow along (Fusion 360’s default settings were way too agressive).

Thats where i saw the project, but they dont go into great detail with how to make the model in the first place. Its very broad description and missing content for someone who doesnt have a lot of experience with fusion360 or meshmixer