So you can totally make an application only with server side technologies because it was how we did before and… it just worked. What is interesting is that all the frameworks, due to their age are very mature.
If you are ok with Python, I suggest you to go through the official Django tutorial, it’s pretty long (some hours iirc) but it covers a lot of topics by guiding you through the development of a complete application.
But other frameworks like Rails, Symfony, are also very mature. ASP.NET Core with Blazor is also nice but IMO, harder for a newcomer because it needs a lot of boilerplate.
All those technologies are pretty boring, but in the good way: they allow you to get shit done without thinking a lot about technical issues.