how to get rid of `Wide character in print at`?

The use utf8 means Perl expects your source code to be UTF-8.

The open pragma can change the encoding of the standard filehandles:

use open qw( :std :encoding(UTF-8) );

And, whatever is going to deal with your output needs to expect UTF-8 too. If you want to see it correctly in your terminal, then you need to set up that correctly (but that’s nothing to do with Perl).