High-density after takeoff, is this normal ????

Hello, I have a youngtimer RAV4 from 2003 for about 2 months now. I notice that the engine first turns up after every start, at the cold start quite to about 2000 rpm for the first 1 to 2 seconds. After that the speed drops immediately to about 1400 rpm and stays there when I start. Is this normal? It is my first petrol for about 30 years, I am used to diesel, the idle at the cold start. That’s not good?! You should not have an engine high hen ?! I didn’t find anything in the instructions, but a bit strange to start driving. There it says: “After starting immediately, don’t run in idle” Next, a little smaller print says: “For vehicles that are not intended for the European market, let run after the start about 10 sec in idle” Is this due to our funny fuel murk mix ??? I basically let my engines run in idle depending on the temperature 10 to 20 sec before I start driving e, I think it’s better for the oil cycle. What do you mean, can you let it turn up after launch, or can you even adjust it?