The current in one transformer loop does not control the current in the other loop.
The power from one loop is transferred into the other, there is no control. The same for two copper wires.
"Control" means that you can determine the value of the power in some circuit by consuming less power to do this. If you have to use the same power, not less, then you are the provider of power, not someone in control, i.e. this is the difference between bosses and the workers commanded by them. The bosses do not lift heavy parcels themselves, they order to some worker to do that.
A device that apparently looks like a transformer but it is an active device is the magnetic amplifier. There are 2 differences from a transformer, the magnetic core is saturable during normal operation (any magnetic core is saturable at a high enough magnetic field, but when that happens in a transformer this means that the transformer has failed, which leads to overcurrents that would destroy the equipment unless a protection is triggered), and the second difference is that the control coil has a very high number of turns, so that a very small current can saturate the magnetic core.
In a magnetic amplifier, the output coil is inserted in an AC circuit where the power must be controlled. When the core is not saturated, the impedance of the coil is high and the output AC current is low. When the core is saturated, the impedance of the coil is low and the output AC current is high. Whether the magnetic core is saturated or not is controlled with a very small current and power on the control coil, which makes this an active device.
Magnetic amplifiers have been heavily used during WWII, especially by the Germans, who had improved them, and they continued to be used for a few decades after the end of WWII, when USA had captured the German technology, because of their very high reliability, until the transistor amplifiers have become reliable enough.