There are so many frameworks out there that already have their ways to connect the client application with the server one and then from the former to a Database, that I'm wondering how someone can build such server applications(for example in C++), then connect them to a Database (for example SQLite) and setup all the network configuration for a server running from home without getting mad

While you can build web servers with C++, it will take much much longer compared to something like Python with a minimal framework like Flask.

If you are keen on using C++, then perhaps you can use NodeJS to handle all server requests and C++ plugins/extentions for speed dependant processes or integrating with legacy systems.

If you don't absolutely need to use C++, then I'd highly recommend Python since it's incredibly easy to learn and use.

P.s. that's my personal take, others can very well have a different view on this.

They do it by using a Framework

Web-Frameworks even exist for C++, you could make a webserver with Qt, for example