Here's a pretty interesting website from the creator of "Children of a Dead Earth" which focuses on near-term space combat ships.
Re:How Do We Prevent War in Space?
by LoSboccacc on Friday October 30, 2020 @08:11AM
(#24941375)
and for a longer term focus, there's project rho realistic designs page http://www.projectrho.com/public_html/rocket/realdesigns.php
https://aerospace.org/paper/physics-space-war-how-orbital-dy...