If you plan on running it in 1080p, go for the 3070 PC, you’ll definitely hit the 40fps minimum for gsync/freesync probably even closer to 60. With the reduced resolution also comes less VRAM usage, so it shouldn’t peak over the 8gb it has. The general raw power of the desktop 3070 along with the cooling potential will also allow it to keep more consistent frame rates. Laptops are known for thermal throttling, reducing clock speeds and producing frame spikes, causing more issues than it’ll solve with the greater VRAM if used exclusively for 1080p.
Really unless you require the Sim to be portable, the desktop is usually the better option in most use cases.