Be careful firing the parts cannon, it can get expensive quick and the faulty part is usually found shooting your last bullet. Better to get a proper diagnosis.
Faulty radiator cap, you can turn the engine off when it’s hot and put your ear to it. You will hear hissing or maybe see staining around the outlet.
When the engine is cold look inside the radiator. It’s easy to see if it’s blocked up.
Faulty thermostat can be found by putting your hand on the radiator. From cold start, if the radiator warms evenly, the thermostat is stuck open. When the engine reaches temperature and the bottom of the radiator is hot but the top is cold, the thermostat is stuck shut.
Water pump is a bit more tricky to diagnose but sometimes they leak. Look for coolant staining around the bottom of the timing cover. A bad water pump can make the engine overheat at idle but when you rev the engine, it circulates the coolant and the temperature drops.
A bad cylinder head gasket can cause coolant and oil to mix. You will have coolant in oil or oil in coolant. Or the coolant can simply leak into the cylinder and go out the exhaust. Don’t worry, I’m sure you don’t have this.
Not always true. Some cars have externally mounted water pumps driven from an exterior belt. I learned the hard way. Just after I started driving my alternator belt broke and the warning light came on so I decided to just drive home and put a new belt on in the morning. Little did I know that belt was also driving the water pump. I was lucky and got away with just a cylinder head gasket. God bless the old days of cast iron heads.