... this example snippet will return a syntax error (near ")["):

my $tmp = 42 + (&((MODES)[1])())[1];

The brackets associated with the & sigil are curlies not parentheses.

Win8 Strawberry 5.8.9.5 (32)  Sun 11/22/2020  2:47:09
C:\@Work\Perl\monks
>perl
use strict;
use warnings;

use constant ADD_DATA    => qw(add    1);
use constant REMOVE_DATA => qw(remove 2);
use constant MODES       => (\&ADD_DATA, \&REMOVE_DATA);

print 42 + (&{ (MODES)[0] })[1];
^Z
43
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But I don't know if this is exactly elegant!