Recently, I received a purchase I placed on Digi-Key. I looked at the physical size of the Schottky diodes I purchased, and wow, they were big. Not just the diode package, but the wires to the diode itself were too large in diameter to fit through the through-holes on my perfboard. No worries, in all other electrical specifications, they were good for my purposes, I just needed to give them a “surface-mount” style treatment to connect them to my perfboard and all was good.
But, the moral of the story, if Digi-Key doesn’t tell you the specific dimensions of a component but just gives you a size code such as DO-204AC (DO-15), then make sure to look up that standard package’s dimensions and verify the component will fit in the board mounting you desire for it.
Here is the Wikipedia article that lists the dimensions info on the DO-204 standard.
20200331/https://en.wikipedia.org/wiki/DO-204
Note that transistors have similar standard size codes, you should check those to make sure you are getting something that will work well for you.