use List::Util qw /reduce/;
say reduce { $a + length $b } 0, @many_strings;
[download]

For cheap thrills, I browsed List::MoreUtils but nothing jumped out at me. This one is similar to yours (both programs produce 21):

use v5.38;
use List::MoreUtils qw/reduce_0/;
my @many_strings = ("abc", "cd", "e", "fg", "hi", "hello world");
say reduce_0 { $a + length $b } @many_strings;
[download]

I'm always out-classed by tybalt89 in these kinds of challenges, so I look forward to seeing what concoctions he comes up with when the USA time zone kicks in. :)

References Added Later

Perl core:

• perllol
• perlreftut
• perlref
• perldsc
• Data::Dumper - core module first released with perl v5.005
• List::Util - core module first released with perl v5.7.3

CPAN:

• Data::Dump by Breno G. de Oliveira
• List::Util by Paul Evans - core module
• List::MoreUtils by Jens Rehsack
• List::AllUtils by Dave Rolsky
• List::SomeUtils by Dave Rolsky
• List::UtilsBy by Paul Evans (some of these might be later merged into core List::Util)
• List::Gen by Eric Strom - provides functions for generating lists; provides higher order functions, list comprehensions, generators, iterators, and other utility functions for working with lists

• How do I adopt a CPAN module?

Other:

• Initialize a 2D array with zeros by cormanaz (2024) -- see response from tybalt89
• The Virtue of Laziness by jo37 (2024) -- wouldn't it be nice to have some kind of "explicit lazy dereferencing" in Perl?
• List::Gen revivified by jo37 (2024) -- fixed long-standing bugs in List::Gen author not responding

• Initializing multidimensional arrays by pearle (2005)
• Re^2: Initializing multidimensional arrays by blazar (2005)

• Multi-Dimensional Arrays and Array References by Leudwinus (2020)
• Fence vs. Posts by rodinski (2018)
• Creating two dimensional array by anonymonk (2007)

• Multi dimensional arrays in Perl (perlmaven)

See Also

• Data Structure References