I constantly experience the problem where an image will display much larger than my window can accommodate. This is at baseline, not after reverting it to original size. So, is there a way I can have images automatically or manually resize to fit within my window? Thank you.

No. Sample versions of images are set to 850 pixels wide with no vertical limit. I don't think there's any resizing code on the page beyond switching between sample size and full size, so you're gonna have to rely on zooming out if you want it to fit.

Have you tried clicking on "Original image"? Both my laptop and desktop automatically size those to fit the screen.

Oh yeah, I forgot about that. Many browsers will auto-resize an image to completely fit within the window if you load the image file directly.