Trying to pin a trope count on a character to judge if they're worthy of being "three-dimensional" or whatever is not a useful exercise, and is frankly about as silly as trying to, I don't know, figure out the ideal number of painting techniques to use in a painting. Tropes are intended to describe media from an audience's perspective and are honestly not that helpful during the creative process because they restrict your thinking, especially when you're inexperienced. I would avoid thinking too much about tropes until you get some actual, presentable work done on your story.
As I've gotten more and more into writing, I've found that there is a ton of shit that goes into making a cohesive story and proper characters that make the story "work" that just isn't tropable.
"Jack, you have debauched my sloth."
Indeed, I'm inclined to agree with CrystalGlacia, above.
"Character depth" is, simply put, about a character feeling to the audience like they're a person, a being with an internal mind of their own.
And, being about an impression, a feeling, different audience members may well feel differently about a given character: where one audience member feels a character to be three-dimensional another might find them unconvincing, and vice versa.
Further, character depth is, I think, less about how many elements a character's depiction is composed of than about how that depiction is composed and presented, and how that composition and presentation works as a whole.
I daresay that one could construct a character with a hundred tropes and yet have that character feel like a cardboard cutout, just one with a hundred bits of frippery tacked on.
My Games & Writing
I'm talking about the 3 depths: 1-dimensional, 2-dimensional and 3-dimensional. How many tropes you need approximately for a certain character to qualify for one of the 3 depths mentioned?