My guess is you’re referring to lats, because most guys can easily pull their shoulders back and feel traps/rhomboids/etc.
The movenent you need to master is movement of your elbow towards your hip when bent over. And the key is to think of it as a swing back to your hip rather than a pull upwards. Might be hard to conceptualize with just words.
Meadows rows, one arm DB rows where your elbow never gets tighter than 90deg, etc.
One great activation is “Joe Rows.” Sit on a Cable Row Bench with a cambered bar attachment. Grab it under hand a bit more narrow than shoulder width. Sit upright, slight arch in your back, head neutral/slightly up. Now think about pulling the bar down to your thigh/hip WITHOUT YOUR BICEP. literally moving the bar just by the rotation of your shoulder joint. Like you’re trying to drag it along your thigh. The cable should be coming down off the pulley, not flat or up.