Is it possible to install linux os on new MacBook Air 2018?

It is possible, but you have to disable Secure Boot:

1. Hold Cmd+R on bootup after you see the Apple logo. This will get you into macOS Recovery.
2. Menu Bar > Utilities > Startup Security Utility
3. If asked for a password, give it
4. Set Secure Boot to No Security, and for the install, set External Boot to allow booting from external media

After disabling Secure Boot, You can install your preferred flavor of Linux (I don't know about the driver situation for the MacBookAir8,1, since it's literally a 2 day old computer.).

~EDIT~

I forgot to mention, but using software like Parallels Desktop, VMware Fusion, or VirtualBox, you can virtualize Linux just like on any computer.

Another thing, if you don't specifically need X11 stuff, most Linux utilities (modern versions of Bash, GCC, Vim...) have macOS versions (you can get those with a package manager like Homebrewor MacPorts.)