Hi @Cykablatta,
Sorry I missed your response.
A few things here, and sorry if I’m repeating infomraiton you already know, not sure where your skill level is at.
Texture samples do not increase draw calls. Things that do increase draw calls is every unique material on screen, the number of un-instanced meshes on screen, and the number of material slots on each mesh. The best place to start for reducing draw calls is limiting your material slots per-mesh and instancing as many meshes as possible.
The number of texture samples increases the cost on the VRam and GPU, which is still very important, but this is why Unreal has a built in texture pooling system (the texture streaming pool). This system caps the amount of memory allocation textures can use, so you never really have to worry about textures affecting performance, only visual quality- because if there are too many high-resolution textures on screen at once, Unreal will automatically mip down to the next resolution for some textures, resulting in low-quality textures (though if this happens you will get the “Texture streaming pool over budget” warning).
Now, if you are trying to limit your project’s VRam use as much as possible, (a very common example being for VR and Switch development as these platforms usually have a shared VRam and Memory) you may want to reduce the size of your texture streaming pool with the console command “r.streaming.poolsize ####” (in megabytes). You can also see your current texture streaming allocation with the command “stat streaming”.
If you are trying to optimize your streaming pool, which is only necessary if you are encountering issues with it, the best place to start is making sure all of your textures are power of 2 and “Never Stream” is unchecked in the texture settings so they are able to be Mipped. Then, make sure you are using your texel density wisely and reduce the default size of any textures that are larger than they need to be. Only then, once these other optimizations are done, is it worth it to look into texture atlasing.
That being said, if you are building your processes from the ground up, it is never a bad idea to start already atlasing. Just do not make any quality sacrifices at this stage. For your given scenario, I would say it’s probably not worth it to atlas major architectural pieces, but if you have the room in your texel density, using trim sheets for assets that are going to usually be in close proximity to one another wouldn’t hurt.
It does sound overall like your main performance concerns are unrelated from general texture optimizations. From the sounds of it, for now I would focus more on mesh and material optimization. I would also mention that 9 times out of 10, the real optimization problems I see from new users is related to lighting and shadowing and an over-reliance on features like Lumen, VSM, and Nanite without understanding proper optimization techniques for their pipelines. Not saying this is you, but just keep that in mind.
Here are some additional resources if you like reading: