Smart tv connection?

I've got a question. I want to buy a smart tv, but don't know what connections I need. Most importantly, I can watch Netflix, YouTube, Amazon Prime Video and Join on them. In my room I only have sockets and nothing else. Could you please help me.

The TV has to be internet-capable, most of them are - or Wi-Fi-capable

As long as you have sufficient Wi-Fi reception, an electrical outlet is sufficient. But if you want to connect a Sky Receiver, for example, you need a satellite / cable connection.