

Most probably, yes. A lot of these are fundamental concepts of most modern object-oriented languages that I am familiar with. It may be worth refreshing your basic programming skills/concepts with a book you like. There are plenty available online for free in C#, Java, C++, Go, etc.
I think what Kualk@lemm.ee is getting at is that Typst also a paid web app developed by a for-profit company. This same company is who manages the github repo for the Typst language compiler. They seem to take issue that this post is promoting a partially open-source project for a for-profit company.