When trying to enlarge the thumbnails of jpegs, some of my folders have an option of the slider to make them bigger or smaller. SOME of the folders, like this one, ONLY have the choice of Two Sizes for the icon. (screenshot). I only recently went up to Big Sur, from Catalina. I don't recall this happening in Catalina, but maybe it did. Is there some setting on that individual folder that would mess with the view options? I've gone to a different folder that Does have the slider option, and clicked on 'use as default' but I guess that doesn't apply to All photo folders? View>Show View Options