While it's not really a tool for precision modelling you can get the objects to real world size by setting the coordinate space and units to your scale. I've modelled the house I'm building in Blender, put it on a real scale and size plot of land oriented against true north. There's even a built in plugin to model sun position based on time and coordinates, it's been mind blowing to be able to see how the shades will change through the windows and how another building will (or not) block the sun during different months.
I've tried FreeCAD for precision modelling like house plans but it was just painful to use, especially compared to AutoCAD which is super good and the snapping is unlike anything I've seen, but sadly prohibitively expensive for non professional use. Their cheapest plan is something like $200/mo.
I’m trying to do something myself but modelling an existing building. I just get really confused on the “right way” too use these tools. For example, on a log building do I model the logs or some flat wall with a texture, etc?
The best way to proceed is to think in terms of placeholders. Make the wall simple now; then imagine how you want to detail it, and proceed with the understanding that you'll want to replace it at some point, and then it's just a matter of setting up the organization of your objects so that that can be done gracefully. If you don't have a particular requirement like presentation in a game engine, you don't have to aim for it to be optimized and can do something like making a detailed sculpt for every log. If you do have that requirement there's still often a reason to push off the optimization to a final step, because it might involve destructive workflows where you essentially turn your initial detailed asset into a reference for the optimized one(e.g. baking a normal map).
As long as you expect everything to be done in two or three iterations and split out the work appropriately, you won't be stuck for too long.
I've tried FreeCAD for precision modelling like house plans but it was just painful to use, especially compared to AutoCAD which is super good and the snapping is unlike anything I've seen, but sadly prohibitively expensive for non professional use. Their cheapest plan is something like $200/mo.