In Unicode, is these a way to superimpose a character over another?

I am looking for a joining character that works a bit like overset in LaTeX. It also works a bit like the many combining Unicode characters, but I would like it to work for any alphabetic letter. For example, I'd like to put a small capital A over an e.

Best I could find was this esoteric Unicode block called Combining Diacritical Marks Supplement, but that doesn't define every letter in the alphabet.

Is there no joining character which puts one symbol over the other?

No, there is not.

As the Wikipedia page points out, there are a variety of combining characters but this isn’t what you’re looking for. Combining characters always define a visible glyph (or none in some cases) which is superimposed upon the preceding character(s).

You could possibly achieve a lot with the characters and combining characters that exist, but Unicode generally isn’t about layout which sounds more like what you want to achieve.