The cruel reality of our current understanding of sport adaptation is that muscle building and endurance training seem to interfere with each other. The more you look into it, it becomes apparent that in order to maximise one you must, to some extent, sacrifice the other.
You can’t fulfil your ultimate potential as a weightlifter and a marathon runner at the same time.
However, endurance and strength can be developed simultaneously to some degree. As it’s often the case with life's most interesting questions, the answer to ‘is it possible to improve endurance without hindering strength?’ boils down to ‘it depends.’