Are these escape codes actually implemented in the average terminal? I recently tried to get e.g. alacritty to tell me this stuff but I don't even know how you're supposed to red back the response.
You just send the particular query (e.g. ‘CSI 14 t’) and the terminal sends back a response in the defined form¹. Of course you'll want raw mode, echo off, etc. Normally a library like curses does this for you. If you want to see, https://gist.github.com/kpschoedel/6a87ec2157ce2140be69193d1... (I just whipped this up to answer the question; don't expect production quality)
¹ https://invisible-island.net/xterm/ctlseqs/ctlseqs.html#h3-F...
It's still in the early phase of development, but actually fully functional.