Don’t use such a dinosaur! Millions of much better performing MOSFETs are available, this isn’t the
1980’s any more - the IRF520 is a truly ancient device.
For 12V 10A load make sure you find a MOSFET rated at 25 to 30V, not 100V, and with on-resistance
ideally below 10 milliohms. Only a small heatsink (if any) would then be needed.
The IRF520 is 270 milliohm, so at 10A its dropping 2.7V (and losing 27W), so it won’t get enough
gate drive even with 12V on the gate (12 - 2.7 = 9.3V). Also its max continuous current rating is < 10A…
With a 6 milliohm device you’d lose 60mV and 0.6W, managable without a heatsink even.
No 100V rated MOSFET can compete with a 20 or 30V MOSFET for on-resistance, so don’t buy a 100V
device for a 12V load.