If you want something practical and productive right out of the box then just go with Ubuntu for any hardware.

Thinkpads are popular in the Arch community (and vice versa), so there's discussion and documentation available if that's your cup of tea.

Do you have link for the Arch community where I can read more about what you are referring to., I am not familiar with that... Thank you !

The Arch wiki has general information and laptop-specific errata for most models:

https://wiki.archlinux.org/index.php/Laptop/Lenovo

It appears the X1C 6th generation doesn't have a page yet, but it's likely extremely similar to the 5th generation one.

Start with the Arch wiki, and go through an installation in a VM. Get your feet wet with what Arch is.

https://wiki.archlinux.org/

What you are really asking is what Linux distro people would recommend. Full stop.

That laptop has Intel graphics, which have great Linux support. It will run practically any distro without any extra effort.

Fedora works well on most hardware I've tried, especially the ThinkPad T & X series. Currently running F26 on a 5th gen X1 Carbon.

+1 for Fedora. I don't have a ThinkPad, but I purchased a Latitude E7470 off Craigslist which already had Windows on it. Sliced the SSD into half and installed F25 on the other partition (Windows comes in handy sometimes). That version had minor issues regarding the headphone jack but haven't had problems since I upgraded to F26.

I read a review about running OpenBSD on them last night. It’s probably wide open to anything.

Yeah, OpenBSD is my litmus test for Linux compatibility. Linux distros like Ubuntu will often figure out how to get questionable hardware working for some value of “working.”

But if OpenBSD runs, it’s a good indicator that the hardware will be extremely well supported and work with the absolute minimum fuss, even if running Linux rather than OpenBSD.