Cable Pulldowns are a great exercise that isolate your lat muscles and help you develop them while minimizing arm engagement.
Load up a pulley machine with weights and a bar attachment.
Using a shoulder width palms down grip on the bar, bend forward while ensuring that your back is straight.
While keeping the arms straight, bring down the bar to the thighs.
After a pause, slowly bring the weights back up to the start position.
Once completing your set, re-rack the equipment as needed.
Move away or towards the pulley machine as needed to ensure proper engagement of the lats.
Try this exercise with the rope attachment as an aletrnative.
Using your core muscles to stabilize your posture will help you better isolate your back.