command to compile typescript in react-native?

I went through this tutorial

https://reactnative.dev/docs/typescript

However, I am using npm and the only command to compile typescript I see in that page is "yarn tsc"

I found another blog that said "npm start" does this but when I add this one line to my typescript, it still compiles and should not since I do not declare a variable something, nor a variable called blah ->

something = blah;

What command should I run to compile/type-check? I am looking for it to fail because of the above line.