Right-o. When the sun is low, there is enough atmosphere between the moon and you to refract some light around and it won’t get pitch dark on the ground. The sun just disappers with the last glimpse of direct light and the horizon looks like it had set.
Instead, you’ll see the mantle of the cone over your head. Nightly darkness fanning out from a few degrees above the sun’s position, with a quite sharp gradient towards a mostly normal evening sky. That is the “black triangle” I’d read about but couldn’t really imagine. Very impressive and nothing you’re going to see elsewhere.
Also, with the sun near the horizon you have the best chance to view partial coverage with the naked eye and without having to obscure the rest of the world. Everyone interested has probably seen many photos of the crescent sun about to set into the Mediterranean already, but since you asked, I’ll share mine as well: