A Best Buy cheapo drone can carry 10lbs.
If you want to bring down an airliner, tape a short length of rebar to it and go fly it into an engine.
FOD is always a bad thing for turbine engines, so yeah a piece of iron would likely lead to a shutdown of the affected engine.
With a decently trained crew, the flight would continue and the passengers might not be too nervous.
An inflight loss of an engine due to destructive failure would likely lead to a short-duration fire and then smoke, but not a crash. The turbine shields are stout.
All passenger aircraft are certified to continue flying (if poorly) upon the loss of one engine.