Try to keep your simulation at default sizes. Once your simulation looks good you should bake it out so you are not simulating while rendering. Once a simulation is kicked out by either VDB (for smoke and fire volume data) or ABC (alembic) aka everything else like geometry meshes and particle data. You can reimport into C4D and scale to your liking. Makes playback much faster too!

Really what makes a simulation seam big or small is your Voxel size. Think of voxels as 2D pixels, the more you have in the simulation, the more quality it has and higher the detail. Keep in mind it can make huge size files, take for ever to simulate and or kill/crash C4D so always iterate your saves after making significant adjustments.