So if you want to test your friends interest an ability I recommend Prairie Mountain. It is a 3.5k one way with 700m of elevation gain through the forest up a mountain and then onto a nice ridge. If your friend can do that and enjoy it then you can pretty much do whatever day hike (NOT SCRAMBLES).
This trail isn’t the longest, it’s all uphill and you can always turn around. It’s 30 min outside Calgary.
After that you need to decide if you are willing to drive 2-3 hrs which brings in all of Banff, Waterton and Kanamaskis into play or if you want to stay closer on less dramatic hikes.
This website is pretty good for listing most of the interesting hikes so if a few catch your eye in terms of distance and elevation ask about them and people can provide feed back
https://www.10adventures.com/hikes/banff-national-park/