The Layout component itself will have to be set in pixels. I can say from experience using it on a larger device (iPhone 12 Pro Max) that it generally creates a nice UI across all devices.
As @domhnallohanlon mentioned above, if you’re working on queries for larger devices (i.e. tablets), using the blocks to help you dynamically change the scale is a great solution.
It’s a bit dated but there are some good examples of doing that there in this thread:
I’ll also use this as a moment to get on my soapbox and advocate for mobile first design approach, designing for your normal “mobile” screen size first and then using the blocks to create media queries for larger devices.