Technically, é (U+00E9) is a character that can be decomposed into an equivalent string of the base letter e (U+0065) and combining acute accent (U+0301).
In the worst case, combining diacritics may be disregarded or rendered as unrecognized characters after their base letters, as they are not included in all fonts.
OpenType has the ccmp "feature tag" to define glyphs that are compositions or decompositions involving combining characters.
On the other hand, a decomposed character set would introduce challenges for searching and editing software and require more bytes of encoding per document.
There is no strict requirement or constraints regarding the relative position between components within a character, the form of variant and transform (narrow, widen, stretch, rotate, etc.)