Highland cows and hiking

Check some of the Daytrip companies like Rabbie's to see what's available from Glasgow. You can do travel surfing on websites such as www.visitscotland.com. There are plenty of excellent places to hike closer to Glasgow then Glencoe which include Castles and Lochs. Glencoe tends to be misty; it is very pretty and green. We were in a car, so we did a drive-by on a cloudy day. I'm from Seattle, so I have seen wet green before and not that many castles at home. We went on to Urquhart Castle on Loch Ness instead. As for the Coos you'll have to do some research.

If you want to be certain of seeing Highland Coos then you don't have to venture outside Glasgow City Limits- just go to the Pollok Country Park- https://www.glasgow.gov.uk/pollokcountrypark

You don't say whether you intend to drive to Glencoe, or to take public transit.

be extremely careful if walking in a field with pregnant cows, at calving, or mothers of young calves. They can charge, and the newspapers often have stories of dog walkers or walkers who have not abided by the advice. And fields with bulls speak for themselves.

I'll be driving.

One day in Glasgow we drove to the Burrell Collection. We passed right by the Highland Cattle Park. You can park off the road and watch the Hairy Coos from the safe side of the fence

You can hike someplace like Callander's Bracklinn Falls which is about an hour from Glasgow. Seeing Coos is a bit of hit-or-miss, like wolves in Yellowstone or Orcas in the Salish Sea. The above idea might be best. They also have a herd on Culloden Battlefield if that's on your plan. Once you've seen them, you'll no doubt run into them on the road the whole time you're in Scotland. On our first trip to Scotland (way long ago) we were delayed by Coo on the road multiple times, and had to adjust our plans to compensate.