% perl -CS -E 'say chr(0xe9)' | perl -CS -nE 'require bytes;  say bytes::length($_); chomp; say bytes::length($_)'
3
2

% perl -E '$x = "\x{e9}\x{3b1}"; require bytes; say bytes::length($x); chop $x; say bytes::length($x)'
4
2

% perl -E '$x = "\N{U+E9}"; require bytes; say bytes::length($x)'
2