What more can you tell us about the Colorado?
What trim level?
What engine?
Personally, I don't care about the mileage, 100K in 2 years tells me it is probably all, if not mostly, highway which is what engines like.
Take a look at the tail pipe, does it look black and does it have a coating that you can rub off with your thumb? That is usually an indication that the exhaust system, and the engine doesn't heat up enough to burn off the excess moisture.
Is the engine bay clean? How about the oil on the dipstick?
Take a plastic baggie and put your hand in it and rub it over the paint finish. Does it feel rough and bumpy compared to just your hand? That tells you that the finish has not been cared for all that well. It needs a full detail job, polish and sealant applied.
When you test drove it, was there a lot of glare on the windshield? If so, have them replace the windshield. It will drive you nuts until you get it done on your dime.
Also, if you are trading in a vehicle, take a look at new ones. They are willing to trade as a lot of people are NOT buying new cars. I got a pretty good deal on my 2021 Canyon Denali trading in my 2018 Jeep Cherokee Limited.