Most of the time our Arm computer does nothing and the CPU is around 40º, and therefore no fan is needed.
But sometimes they work a lot and the fan is really necessary.

So I wonder if a 5V fan connected to the gpio pins can be used and that the same board sends power to the fan when for example the CPU exceeds 60 °.

And below 60º the orangepi that cuts the current to the fan.

Can it be done without external components?

I dont think the GPIO line had enough power to drive the fan.

I think you should wire the fan to the normal 5v line and put a switching device like a relais or switching transistor in the fan powerline connected to the GPIO or I2C line.

then you can read the temperature via script and switch the fan on/off with the script.

another idea would be a bimetal switch in the 5v powerline of the fan (so no script control)

Just my 5 cent

Tnx... good ideas, I will study them