In theory you can run MacOS under a virtual VM:
https://forum.parallels.com/threads/can-i-use-parallels-to-run-el-capitan-under-high-sierra.344269/
However there are a lot of gotchas. I just tried to download Sierra on my iMac Pro and got this error message:
View attachment 778058
Since you have a new machine I assume you would have the same problem.
I then tried to download it in a Parallels Windows 10 VM and got the messages:
View attachment 778061
View attachment 778062
Got the same message when trying to download in Firefox running in High Sierra.
You can get the install image in other ways. But will Parallels run a version of MacOS that is not supported on that hardware? Don't know.