The newer FWD Aisin 6 speed autos have a two stage drain process.
First one is the drain plug itself, and the second one is the 'stand pipe' that you remove from the drain plug hole.
Refill exactly what you drained out. Usually I get around 2.5 or so quarts out.
Its messy but can be done. Make sure its stone cold (sat overnight).
If you really want to change the filter, you'll have to lift the engine/trans up to get about half a dozen bolts that are obstructed by the K Member.
FWIW, I have a customer with a 2010 RX and 230K, and all we've done is 60K ATF intervals (no filter). Still shifts like new.