The trunk may be smaller than the C7's, but the frunk closes much of the distance
Among sports cars, the Corvette has long been one of the best choices if you actually plan on driving the thing somewhere and bringing some luggage along with you. There was a relatively vast amount of space underneath the coupe's hatch and a decent amount of space for a convertible. Specifically, the C7 had 15 cubic feet in the coupe (below left), which is comparable to a midsize sedan, and 10 cubic feet in the convertible (below right), which is usually what you'd get in a coupe.
Of course, with a switch to the mid-engine layout, the C8 Corvette has a radically different body style than its predecessors. The trunk (below left) is substantially smaller and you don't need to look at the specs to know that you can't fit as much stuff back there. However, as it's a mid-engine car, there is now also a frunk. The result is a shared total capacity for both C8 Coupe and Convertible that splits the difference between the old C7 versions at 12.6 cubic feet. As that represents the total of trunk + frunk, though, it's hardly comparable to the listed volumes of other cars, including previous 'Vettes.
It's obvious that the trunk is nowhere close to being as long as either the C7 coupe or convertible trunks. It's quite deep, though, although it unusually slopes downward like a trench and pinches in at the corners, which may impede your loading.
As for the frunk, Chevy doesn't break out individual cubic-foot measurements, but its shape is similar to what you'd find in a Porsche 911 or 718 Cayman.
With a trunk and a frunk, comes two buttons on the key fob. AND! since this is the convertible, you also get a remote roof-opening button. Nifty.
Now let's get to the bags, and let's face it, they're not all going to fit. You can forget about the two biggest bags you'd need to be checked in at the airport (26 inches long, 16 wide, 11 deep). Besides those, I use two roll-aboard suitcases that just barely fit in the overhead (24L x 15W x 10D), and one smaller roll-aboard that fits easily (23L x 15W x 10D). I also include my wife's fancy overnight bag just to spruce things up a bit (21L x 12W x 12D).
The two larger carry-on bags fit in the trunk together, but it was a very tight fit due to the pinched ends. Not surprisingly, the fancy bag fits much better. There was also some space left over below in the trench.
In total, it's a weird space, but hey, two decent-sized bags for a two-person car? Not bad! And remember, there's more space up front.
For the frunk, the smallest roll-aboard fit perfectly (right). One of the larger bags (left) barely fit, and the other one would not. You can't really fit anything else on top except maybe some shoes or a small shopping bag.
This means the frunk is smaller than a 718 Cayman's, which can stack both of these bags up front (I lifted the bag up in the photo below to show the bag below). It can also fit the other roll-aboard in its trunk, plus the fancy bag and other items atop the engine.
So, the C8 Corvette's not quite as good as the 718 or the old C7 Corvette, but at least according to the specs, it's better than the C7 Convertible. Either way, the C8 Corvette remains very luggage friendly compared to other sports cars. Go ahead and plan that road trip.