Good Question...
Most golfers have an open clubface and swing dead left to "start their slice."
When you swing down a plane—any plane—with a base line pointing to the target, the WHOLE DOWNSWING is "inside-out" so to speak.
That's where all the TGM types got hooked on this idea—which btw is great for lots of folks who need it.
But, you should hit the ball very near low point, and this will make for only a slightly inside-out hit—if you have a straight base line.
So, soon as the club reaches low point, it will move back UP THE PLANE, or "outside-in" so to speak. Most call it "up & in."
The hips lead the parade on the downswing, and an orthodox procedure would have the hips 40-60° open at impact.
Also, the hips SLOW to a near stop in a PERFECT SWING, so if you let the club do what it should—go back up and in.....
You can have it all, a inside-downswing, an online strike, and swinging past your left leg.