It's possible to identify non HTTP running on port 443?

I need to develop something similar to ngrok as I have a group of machines that run behind firewalls and the only communication is trough 80/443.

The idea is to establish a TLS connection on 443 to a central server and use this connection as a tunneling point to run a SOCKS5 server.

And the question is, firewalls are able to identify that I'm not running HTTPS on that port? Because the initial communication will be different.