Tall receivers need to work on 2 main things in my opinion. Their physicality and their ability to change direction at the top of the route. If you are taller and bigger than most DBs, use it to your advantage. You are most likely stronger than them. Practice your hand technique at the line of scrimmage and attacking the points of control on a DB. (Elbows, forearms, back of shoulders/arms) For taller guys it’s more difficult to sink their hips at the top of the route and get low so you can change direction faster. That’s the name of the game. If you can develop great balance and explosiveness at the top of your route, while being a bigger guy, you will get a lot of separation. A good guy to study is Julio Jones. He’s not suppose to move like that at 6’4. But he’s dangerous because he can sell vertical, make everything look the same and snap down fast at the drop of a dime. You can too but you need to work on your hip flexibility, balance at the top of the route, and explosiveness at the top of the route. Those are the main things tall receivers need to work on.