OK. I attached a video. Its a newer Avalon, not very descriptive but give you an idea of what to expect. Will add some details.
Before opening the drain, open the radiator cap to relieve pressure to the system.
As you can see in the video your unscrewing the drain, but not all the way. This allows the coolant to drain out the small drain spout, not splash all over the place.
Depending on what you catch the coolant in, you may have to jack the car up a little bit to make room for the container under the coolant drain spout. In the video he's using a standard oil drain pan so no need to jack the car. Thanks to the drain spout I can go directly to a jug, so I lift the car with a floor jack to make room.
The expansion tank is most likely the same as the video and my Camry, not bolted on. Just lift it off the slide bracket for cleaning.
You should get 4-6 qts of fluid on the drain. Once you dilute the Toyota LLC red concentrate 50/50 with distilled water (NOT spring water) from the grocery store you will have 8 qts of coolant. Enough for the drain and fill, refilling the expansion tank, and some top offs.
Important step not mentioned in the video - After you tighten the drain, refill the radiator and the expansion tank, don't put the radiator cap on yet. At this point start the car without the cap, but have it ready to put on. You will see the coolant flow, maybe drop a little. Add more coolant to the radiator. After about 30 seconds you will see the coolant start to rise as the engine warms up, pushing air out of the system. Just before the coolant overflows, put the cap back on.
Let it warm up and watch the temp gauge. Your watching for the temp to stabilize at or below its prior setting, which means the thermostat opened and the system is functioning properly.
Does this get it all? No, there is a small amount of residual. But thats ok, the system expells any junk into the expansion tank. Clean and refill expansion tank when it gets low or once a year. Your good for another 3-4 years/50-60k on the drain. Then do it again. Could you go longer? Yeah but that seems to be the tipping point for me anyways. And I havent replaced anything with this method.