Pour in some coolant of Toyota long life or caltex and then use car, after it heats again. Pull out the radiator.
You'll find out the points from which the coolant is leaking.
And any minor hole in cooling system can air lock your cooling system Making the car to heat.
So do this test. If you don't find any leaks.
Then you should do the gasket leak test.
Videos are on YouTube.
But first do this coolant test.
You can't find out the leaking point with water. Since water evaporates.