Some bits in the instruction activate some logic gates in the instruction decoder that, in turn, activate and deactivate other logic gates in the control logic,

Some bits in the instruction activate some logic gates in the instruction decoder that, in turn, activate and deactivate other logic gates in the control logic, and eventually the appropriate functional unit inside the CPU is configured for the thing the instruction calls for and does it. Like the ALU adding two numbers together. If it's an architecture that uses microcode, like everything x86, I suppose the instruction decoder instead (or additionally?) outputs a microcode ROM address.