$ perl -E '
    use strict;
    use warnings;
    say ref my \$scalar;
    say ref my \@array;
'
The experimental declared_refs feature is not enabled at -e line 4.

$ perl -E '
    use strict;
    use warnings;
    use feature "declared_refs";
    say ref my \$scalar;
    say ref my \@array;
'
Declaring references is experimental at -e line 5.
Declaring references is experimental at -e line 6.
SCALAR
ARRAY

$ perl -E '
    use strict;
    use warnings;
    use feature "declared_refs";
    no warnings "experimental::declared_refs";
    say ref my \$scalar;
    say ref my \@array;
'
SCALAR
ARRAY