It's not clear precisely what you question is; could you rephrase it?

I think you are asking how to make the caps more harmonious with the lower case.

That is a complicated question. In the history, in the 15th century, scribes for the first time started using together the Roman Imperial Caps and the Carolingian minuscule—two different alphabets. And then they harmonized them by making the lower case more like the Roman, making serifs more symmetrical, and the stems more vertical. When they started cutting type, these tendencies became even more pronounced.

They are still two different alphabets with different structures in most characters. In recent times the tendency has been to make the caps smaller and lighter so they are more the same typographic color (same gray) with the lower case. How similar they should be made is an open question, because caps are used partly in contrast with lower case.

If you wanted to make them really harmonious, you would just do away with the caps. The Uncial style was is similar to lower case, and could be used in place of caps, but is not as harmonious as just doing away with caps. But as of now, most designers don't really want totally harmonious.