If you’re really looking to improve lumen reflections to the extent that you can, increase the distance field resolution scale of a given mesh; it will at least make near-field reflections better, at a very large memory cost. To add onto @BananableOffense , planar reflections are the only non-HWRT reflection solution that can do parallax-correct, Gbuffer-accurate reflections, but they have a very large and geometry-dependant cost.
If you needed to do ArchVis with just SWRT, you could likely increase a number of settings and distance field resolutions to get acceptable results, but good mirror reflections are simply not possible on anything but the highest scalability levels with HWRT.