I hope this is the right place to post this, it’s sort of complicated and I’m not sure if this is the right category. TL;DR, it’s a question about worldbuilding approaches/resources.

First, some background: I’ve been working on building up a fictional world for my current novel project. The world is not really intended to break any of the known laws of the universe (besides maybe a few, but nothing to do with anything that would show up on a map), so basically, it’s just going to be Earth with different continents. The main premise of my worldbuilding is to see how different of a planet I can end up with from Earth without changing anything dramatically (i.e., humans are still humans and facing a similar world). I have an idea of how I want my continents arranged (large polar continent at the North Pole which extends down to the equator in the east, equatorial continent to the west, and a small (Australia-sized?) continent in the south). The main action of the story takes place on the Southern Continent, which I’ve already got quite a few sketches of, and there’s some action later on in the southernmost area of the Northern Continent. Besides that, everything else is technically not relevant, although I would like to have some idea of how the continents are arranged/continental drift/etc, for planning out human and evolutionary history.

I’ve seen a lot of resources on here as well as other parts of the internet that are really great for figuring out scientifically-accurate pictures of a whole world, but I haven’t seen much for doing specific regions. If I had endless time on my hands, I’d love to create a world map, but currently I think I need to scale back my expectations. In that spirit, I’ve decided that the most important thing for me is working out interesting local features—any tectonic activity, geology, things like fossil deposits or mineral veins, etc—for the Southern Continent. I still don’t want to close off the possibility of creating a whole-world map at some point, though (I’ve caught a terrible case of the worldbuilding bug, if you couldn’t tell).

I guess my question has a few parts. First, should I just focus on making maps of the places that matter in my story? If I end up wanting/needing to expand the boundaries of the map, how hard will it be to retcon things, and what things should I avoid defining until I’m sure of my boundaries? Second, how should I go about creating the region-specific map if I want it to be scientifically accurate? Third, does anyone have any advice/tutorials/references for what smaller geological features I should be thinking about on my regional map? There’s a lot of stuff on the internet about volcanoes and mountain ranges, but not a lot about microclimates or unusual veins of rocks.

Apologies for the very long post; brevity is not one of my strong suits, so let me know if any of what I said is confusing. Hope this hasn’t been covered a million times already, I’ve looked through stuff but I’m still very new here haha

(I'd also love any advice about how to say no to worldbuilding I don't need to do, I'm currently having a lot of trouble setting boundaries there )