But let's talk about what a war would look like from a tactical perspective. As far as I know from the lore, there hasn't really been a 'real' war in interstellar space, things have been in a cold war for centuries. That creates some interesting issues because there isn't a track record for what works when major powers actually throw their weight around. This thread is now about what a war like this would look like.
The thing that would control combat is how FSD drives works. Due to FSD technology, there is no definable fronts. This makes taking and holding territory very difficult, but disrupting enemy supplies and destroying material very easy. Most combat would be analogous to airstrikes and piracy.
“Space Strike”
When you can hop from system to system in seconds, there is no way to set up a sustained wall of resistance. All you can do is react. If all your defenses are on the border systems they will be essentially useless. An enemy fleet could warp in and out in 30 seconds, heading towards some target. the defending fleet doesn't have enough time to interdict anyone from this first contact, and are now stuck being forced to scan the wakes to figure out where this fleet is heading. That extra step makes it extremely hard to catch up unless you have organized advanced scouts warping around to various systems to keep track.
This would only change once a fleet has to stop to scoop fuel, giving defending fleets a chance to catch up and start interdicting ships. Intelligent commanders could arrange for fuel support ships to advance ahead of a fleet and provide limpet supplies to keep things moving faster, or at least to allow resupply to take place in normal space where it would be just a bit harder for defending forces to keep track of your presence. Even more intelligent commanders would send a fleet outside the bubble to carefully maneuver around to find the shortest distance to their target.
The upshot of all this is it would be relatively easy to make deep targeted strikes into enemy territory. Jump in, destroy or severely damage a space station, and then head back home. To counter this, you would need to have dedicated defenses at every star system in anticipation of such attacks. You could have as much as 80% of your fleet set up as dedicated defenders in these systems, or severely leverage local militias.
“Piracy”
A more accurate analogy may be ‘unrestricted submarine warfare’ but the effect is like piracy just without caring to actually steal anything. If a dedicated fleet can dash into the interior of enemy space easily, then multiple wings of ships could spread all over enemy space and start blowing up any targets of opportunity, destroying trading vessels and the like. It’s another example of how it’s much easier to damage the enemy’s economy than to take the enemy’s territory.
All that being said, I think the Federation and Empire would totally try to take territory. This is where distance becomes much more important. The supplies needed for an army that would be needed to take over and occupy a space station are huge, and imagine trying to conquer a planet. This means a need for constant resupplies of food and other material. In order to maintain supply lines you need space superiority. If the defenders manage to blockade the space station, your soldiers will be having a bad time. Then...it becomes a question of smugglers. We could see a fun new smuggling option. When a system is blockaded, you may be attacked just for being in the system, no matter what you have in your cargo hold.