Do make sure anything you choose is intended for outdoor use so it will last longer. The more sheer items will not prevent you from being seen if you have a light on above and/or behind you.

There are curtains intended for outdoor use that are semi-clear. You might want some tie backs as well.

https://snowcityshop.com/products/patio-curtains-uv-protection-thermal-insulated-privacy-guarantee-grommet-top-blackout-indoor-outdoor-drape-100-inches-wide-1panel-%E7%9A%84%E5%89%AF%E6%9C%AC?&currency=USD&gclid=EAIaIQobChMI4O26mpOf5QIVEMDICh3dzAFVEAQYASABEgLZ8PD_BwE?variant=17041202053166

The pull down roll shades can help and be more neat in appearance but your privacy below the railing depends upon your closing off the area above.

https://www.pinterest.com/pin/708402216372695064/?nic=1

Horizontal mini-blinds or vinyl vertical blinds will give your more options as to light and privacy controls because you can open/close them in more than one way.

If allowed:https://www.amazon.com/Patio-Backyard-Gardening-Protection-Brown-Custom/dp/B07666J91Z/ref=asc_df_B07666J91Z/?tag=bingshoppinga-20&linkCode=df0&hvadid={creative}&hvpos={adposition}&hvnetw=o&hvrand={random}&hvpone=&hvptwo=&hvqmt=e&hvdev=c&hvdvcmdl={devicemodel}&hvlocint=&hvlocphy=&hvtargid=pla-4584001418550999&psc=1

https://www.blinds.com/p/blindscom-outdoor-solar-shade/505227?width=16&height=20utm_campaign=acqsembc-b-pla-exteriorSKU%20(NEW)o5052271620cNTMbe%7badposition%7d&utm_medium=pla&utm_source=bng&utm_term=&utm_content=&msclkid=e622297768a11a0d779d74d15d1c3832&utm_campaign=bc-b-pla-exteriorSKU%20(NEW)&gclid=CLnhoc6Xn-UCFZLgswodNOIDFg&gclsrc=ds

How deep is it? Do you have furniture there?

I have seen fabric woven through the spindles. "Across the way" looks like it is lower, so any view would be interrupted unless you are standing at the railing.

Are you allowed to attach anything to the wall or must it be freestanding?

A few potted bamboos might work well there.

Summers, I was also thinking along the same lines, but could not tell from the pic how deep the balcony is.

The main privacy issue can be fixed by attaching a privacy curtain (waterproof) from the railing with Velcro or plastic cording. Perhaps two plain narrow shower curtains would work. Attach the material in several spots along the bottom rail also so they don’t flap in the breeze.

Thank you all for your thoughts!

Regarding some of the questions:

1. I can attach things to the wall if needed.
2. The depth of the balcony is 6ft.
3. I don’t have any furniture there right now.

Also, I know I could take care of some of the privacy concern by just covering the railings—and I’m considering it—but it’s also occupants in the tall buildings that are behind the complex right across mine that I’m trying to keep from peeping. (I’m not crazy, I’ve seen them and this photo might not reveal the buildings further to the left I’m referring to)

I want the railings to be 100% covered (permanently/Blackout/zero visibility.)
Then i think some sort of outdoor curtains that I can close and open as needed. The 24ft long Balcony just seems tougher to get the right sized coverings for.

IMO you are higher than the other building so what is your issue and what are you doing on your balcony that requires so much privacy. In most apts. there are rules about what can be used on the balconies so maybe check there first.

What did you do?

If nothing yet or ready for another change:

https://www.google.com/search?q=canvas+tarp+as+curtain&client=firefox-b-1-d&sxsrf=ALeKk00nQ5iuRwzaMeApGGXnfvL-jC3VpQ:1599888243582&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjbkcGT8OLrAhVjlXIEHVZuBrAQ_AUoAnoECA4QBA&biw=1366&bih=654

what are the dimensions of your balcony?