Second to your GPU, your system's RAM is probably the most important component when working with Twinmotion. If you upgrade your RAM capacity, you should notice some performance improvements and fewer slowdowns, especially if you work on detailed projects with lots of geometry and texture data. System RAM isn't utilized the same as GPU VRAM, so you won't see most of your RAM being utilized if Twinmotion doesn't need it, but the extra capacity should leave resources free for multi-tasking without worrying about degraded performance.
64GB of RAM should be sufficient for most workflows, and 128GB is generally only needed if your projects are very large or extremely detailed.
Your GPU and CPU high-end enough that you won't need to be concerned about having to upgrade these for a while.