How can cameras with RTSP like Tapo cameras be accessible from the outside?

I wanted to know how these cameras work when it comes to redirecting traffic outside the local area network (LAN) of your home. In other words, you connect them to your phone, configure them, connect them to the internet, and then they are accessible from outside using the app. However, they never provide the RTSP address for you to use your own application. As far as I know, you always need to use their apps. I was curious to know how they work. Do they have something like No-IP built-in? Do they create a tunnel to a specific server? Additionally, is it possible to obtain those RTSP URLs? Or do Tapo servers handle all the traffic every time I want to connect to my camera through their app?