Do I need a flange extender

I just completed tiling my bathroom floor. However, now the top of toilet flange is level with the top of the tile.
Do I need to install a flange extender or will a single plan wax ring work?

The toilet I'm installing is a neorest 500 it came with an odd adapter that installs onto the flange and screws to the floor.

If the wax squishes top to bottom, you will be fine.

https://terrylove.com/forums/showthread.php?t=14022&highlight=neorest+500

How much does it have to squish? It looks like it'll go about 1/2 inch. Or should I maybe use a fatter wax ring to be safe?
Can I stack 2 wax ring together?

Like Terry said, just needs to squish all the way around the flange. Yes, you can use a thicker wax ring, or 2 wax rings - but probably don't need to from what you've described.

Do avoid the use of wax rings with a plastic horn or funnel - these have been known to cause restrictions.

The Toto "UniFit" system you are using is really a neat way to install a toilet. If you ever want to pull the toilet for some reason (like to paint/paper behind it), it's very easy and you don't need to replace a wax ring.