I would separate source resolution from delivery resolution. Capturing above 4K gives you room to crop, stabilize and reframe. That does not force the final file to remain at the camera's native dimensions.

A 4K master can preserve more detail and give the platform a higher-resolution input, but it also costs more encode time, upload time and storage. A good 1080p downscale from a high-resolution source can look excellent.

Do a short controlled test rather than arguing from resolution alone. Export the same thirty-second section at 1080p and 4K using sensible quality settings, upload both privately/unlisted, wait for processing, then compare the actual playback versions you care about.

Fast motion, foliage, water and fine texture are good stress cases for action footage because compression differences become visible there before they do in a static talking-head shot.

In VSDC I would keep the project at the resolution that makes sense for the edit, then make delivery presets rather than changing the source workflow. If you need a 4K YouTube master and a smaller 1080p copy, render both from the same finished project.

The key is to avoid using a previous compressed upload/export as the source for the second version. Both deliverables should come from the project and original media.

For long travel videos I sometimes choose 1080p simply because the upload window matters. For short scenic/action pieces I usually keep a 4K master because storage is manageable and I like having the higher-resolution archive.

So I do not think there is one universal answer; delivery time is part of the production constraint.

I will run the private-upload comparison on a fast biking section. That should answer the question for my channel better than assuming 4K is automatically better.

I also like the idea of keeping the project resolution separate from the delivery presets.