Installing a 24 to 12 volt convertor for this is like using a sledgehammer to kill a fly. It WILL work, but is an insanely complex and expensive solution to a REALLY simple problem. I am a very big fan of Victron equipment, but it really is not the right answer for this problem.
A relay is a bit better, but still much more complex a system than needed.
All you need is a resistor. Measure the resistance of the clutch coil, and install a resistor in series with it that is as close as you can to match it. If it costs more than $1 you are overpaying.
Ohm wrote the law. Take half the voltage drop across the resistor and half across the coil. 100% reliable. Just chose the right resistance and power rating.
We have been sailing for 5 years with a B&G 24 volt clutch output feeding a raymarine drive just using a 25 Watt/30 Ohm resistor (over kill, but it was so cheap not worth fine tuning) in series to take half the voltage drop. The clutch is happy, the drive computer is happy. I am happy because the whole setup cost $0.89 and has no failure modes I can see.
Keep it simple.