É explicado no less
FAQ Pode exibir menos caracteres de idioma não inglês?
Less has two ways to display non-English characters. If your system uses a non-ASCII single-byte character set, you should set up your system with the correct "locale" settings. If your system does not support setlocale, you can set the
LESSCHARSET
orLESSCHARDEF
environment variable to tell less what language you are using. See the section "NATIONAL CHARACTER SETS" in the man page for details.If your system supports the UTF-8 encoding of Unicode for non-ASCII text, as many modern systems do, you should either set your locale to something that includes the "UTF-8" or "UTF8" (either uppercase or lowercase is ok), or set
LESSCHARSET
to "utf-8".