Typically there should be a maximum size in bytes for performance reasons (e.g. how many rows fit in a page) and/or a minimum size in "characters" (very ill def

Typically there should be a maximum size in bytes for performance reasons (e.g. how many rows fit in a page) and/or a minimum size in "characters" (very ill defined but usually approximated as code points, with some slack to allow a reasonable amount of combining marks in addition to the desired number of letters), with no guarantee that the two sizes are compatible. I've often found in practice short UTF-8 columns with a bytes length, that "accidentally" truncated text with ctastrophic effects after the application checked value lengths in characters.