I can't open it right now but I'm pretty sure you right click anywhere around the bookmarks bar (NOT a bookmark) you get an option to customize the UI/bars and there's a checkbox for icon size
Unless I'm completely mixing this up with Chrome but I don't see that here.
Nope, not getting any of that. If it ever existed, it's another casualty in the war on configurability. There's an option to add more space between the icons, but they're still as tiny as they ever were.
It still exists. Customize Toolbar -> Density (bottom left). There are only 2 or 3 presets, but it is possible to slightly adjust the icon size. Just confirmed on 109.0.1.
You may be right. I checked before replying, but I may have just been tricked by an optical illusion with the extra padding shifting everything.
By default there are only 2 densities, but there used to also be a "Compact" option which was removed. I believe it is possible to still enable this, though it is officially unsupported at this point.
Unless I'm completely mixing this up with Chrome but I don't see that here.