Shoulders and back exercises alone are not enough. The body is a single whole small muscle groups such as shoulders and arms for example grow very poorly if large muscle groups are not trained. So without squats and bench presses, it will be hard to achieve results.
Also, I would not recommend the bent over row for beginners, as this exercise is traumatic enough if the back extensors are not developed enough. Therefore, it is worth replacing the bent-over barbell row with horizontal pull-ups or reverse grip pull-ups.
There are many techniques for working on the muscles of the back, most coaches today agree that two movements are needed to fully work out the lats and upper back: pull-ups with a wide grip (as well as analogues of this exercise) and pull-ups with a reverse grip (and analogues). However, for those who find it difficult to bring their back to failure in at least one of the listed exercises, the method of preliminary fatigue is more suitable. First, an isolated exercise is performed, and then, without rest, the basic one. This method was described in detail by Mike Mentzer in his books.
I would not recommend the army press to beginners either, as this exercise, with the wrong technique, wears out the shoulder joint a lot. And the front delta, which takes over the bulk of this exercise, and works so well in the bench press. The most optimal exercises for the shoulders, I consider a horizontal broach, as well as swinging dumbbells to the sides and pulling the bar to the chin. The last two exercises I would perform with a slight forward bend of the torso, as this reduces the risk of injury. These three exercises are great at working out the back and middle deltas, which tend to lag behind many athletes.
Naturally, basic, that is, multi-joint, preferably with free weights, or on a horizontal bar, namely: for the broadest muscles, various pull-ups, preferably with a wide straight grip, for the muscles of the shoulders, an army press standing. -Row or barbell row in the slope, grow muscles in thickness. If I understood correctly, then the question concerned precisely the deltoid and latissimus muscles, but if we mean the shoulder girdle as a whole, then I would add squats with a barbell with deep breaths (yes, yes!), It would seem, they say, like an exercise on the legs ( yes, that's right), that is, the nuance - behind the bar, pressing on the chest, expands it with a deep breath; then, bench press, although there are doubts about this. And also for aesthetics it would be nice to make the waist narrower, for this there is such a wonderful exercise as a vacuum, no exercise for achieving a V-shaped upper body can be compared with it.
By the way, at the age of 18 most people still have their growth zones open, so hurry up, there is still enough time to fix the issue.