Luggage larger than 21 inches are considered suitcases even though they may match the carryon that you have. Most suitcases have wheels now, and they are made to be easy to maneuver with minimal carrying.
It wasn’t that long ago that the image of a man carrying all of the bags for his entire family while struggling up the steps was actually a thing we still did. Now, most bags can push along beside or behind us and hold way more of our stuff than they look like they should be able to.
Suitcases come in a variety of sizes from carryon all the way up to more than 30 inches. I’m sure there are bigger ones out there, too, I just haven’t found them yet. Keep in mind that bags that total more than 63 inches when you add up height, length and depth can result in a hefty oversized luggage charge.
Suitcase options are so varied, that I did my best to capture an accurate cross-section of what the industry has to offer.