To be on top in tech skills is need to this time, frameworks are evolving and new ones are coming in market in bulks. As a developer and software engineer your skill will standout if you have latest tools in your hand, may be you don't agree but this can be experienced more in high posts as you grow in your career. The only purpose of above talk is, "Update your visual studio and get c# 9 in action".
To start working with c#9 make sure you have installed dot net 5 sdk in your system and you have visual studio 16.8+ on your system. One you done that restart your visual studio and go to project properties you will find dot net 5 in target framework which includes c#9 by default. Wasn't that easy one step process. If you still have confusion, you can follow my youtube video : https://www.youtube.com/watch?v=oQmVxfIsW_Q ( and subscribe to my channel ).