SUMMARY

libkscreen in 'Plasma 5.27.0 Complete Changelog' lists:

Add zsh completions (compdef) for kscreen-doctor.  

STEPS TO REPRODUCE
0. Install kde neon with latest Plasma 5.27
1.  start zsh:   type kscreen-doctor<tab><tab> # no completion info
2. dpkg -L libkf5kscreen-bin  # contain kscreen-doctor but no zsch completion

OBSERVED RESULT
no working completion

EXPECTED RESULT
Citing commit :-)

Top-notch context-aware completions for kscreen-doctor with fine-grained
tags, descriptions and dynamic selection of outputs and their available
modes. In the output completion menu it displays status of outputs and
sorts enabled ones first. In the modes selection it brings current mode
to the top (if any), then lists output's preferred ones, all marked
accordingly, and finally dumps all other available modes. All modes are
pretty-formatted to be nicely aligned and easily distinguishable while
inserting correct compact mode ID upon completion.

SOFTWARE/OS VERSIONS
Operating System: KDE neon 5.27
KDE Plasma Version: 5.27.0
KDE Frameworks Version: 5.102.0
Qt Version: 5.15.8
Kernel Version: 5.15.0-60-generic (64-bit)
Graphics Platform: X11