Does the radiator have an external overflow?

I have a '93 Cabriolet. I've noticed lately a small puddle of coolant under the car after long drives (doesn't appear after short drives <10 mins). It appears the coolant is coming from under the radiator.

Before I suspect the radiator of having a leak, is there an actual overflow for the radiator (as opposed to the overflow tank/resevoir) that leads to the ground?

No I would suspect and inspect the plastic radiator flanges on the block.

It could also be a hose clamp on a main radiator hose.

Front center is usually the plastic flange on the block.

Front and to the left the plastic t-stat housing or water pump

Front and right is the plastic flange on the side of the head, the heater valve, the expansion jug, or hose

Rear of the engine and to the right is usually the heater core (matrix) hoses.

If you have a UV penlight, and are running the old green prestone a/f it will show up under uv light.

I would also check the expansion line running between the tank and the fitting to the left of the radiator.
Take care in removing that line off the radiator as it is better to cut it off than trying to pull it and destroying a possibly good radiator.

While it could be a pinhole int he radiator tanks (plastic) in all my cases of early 90 cabriolet ownership it was always the flanges cracking at the mounting ears.