We will be flying into Trondheim and have three days in that area. We would really like to see a fjord or two, as well as other beautiful Norwegian scenery, but probably don’t have time to go to the usual sites on the West coast. We can rent a car to help us get around. Please offer suggestions for day trips from Trondheim as well as things to see in Trondheim itself. We’ll have a 13 and 17 yr old with us and mostly want to be outdoors.
This thread may help you as well.
300 km away is Andalsnes - so over-night stay there is recommended. Fjords around Trondheim are nice but less scenic.
Closer, somehow scenic but no fjord is Trollheimen mountain area.
VisitNorway shows some tips what to do in Trondelag state.