I already gave up my green thumb at birth...
For your container planting, you need a green thumb. Normally, these plants take care of themselves: they draw their water from the soil (except, of course, in the planting year) and grow independently. Possibly sprinkle some horn shavings over them in spring.
Then they develop normally and grow in width in their clump. By the third year, they should have formed about 3-4 times the circumference in the clump.
That they are a bit too close together is true, I might thin them out a bit if it gets too much.
You probably won't even notice that because the individual plant lacks the soil volume to spread out. You planted bedding plants there.
They cannot draw nutrients because they lack space in the tightness and have to share these nutrients. You would always have to fertilize afterwards. Diseases multiply due to the closeness, and to recognize that, you need a green thumb.
If you want to remove some in autumn, the roots are already so entangled with each other that they won't remain undamaged. Your planting containers as well.
Your flowerpots are good for small plants.
If you want immediate privacy screening, you would have to go for an already 180 cm planting height or initially set up a privacy screen. For the latter, 40? cm width would also suffice.