There are some technics for fitting a good amount of components in a turret. you can embed the turret into the hull of your ship to minimize the bulge, your turret creates.
You can also try to expand the shell by using hull blocks type: slap.
The technics highly depends on the shape of your ship and the shape you wanna build your turrets in.
I recomend the following starmade thread to get insiration:
Depending on how much area coverage you need, there are a few options for turrets.
- If you're flying a relatively nimble craft and simply want the computer to do the aiming for you, you can build a turret using only one turret axis. This type is incredibly easy to conceal and can be made to look like an integral part of the ship. You can build around it so that it only faces/fires forward or you can build it in such a way that it can fire in up to 360 degrees on one axis; requiring you to bank (roll left or right) to hit targets on the other axes. Both methods can be hidden or exposed depending on your needs or creativity.
This kind of turret can also be used as heavy frontal assault for larger ships but puts you at a disadvantage if your banking/rolling speed is too slow or someone gets behind you.
- If you want a defensive system that will engage targets in any direction, you'll need two turret axes. This turret type is good for use against fighters and missiles but needs to be very large if you're fighting other starships. Concealment is a lot harder unless you have recessed housings that they emerge from during a fight. In most cases, style and concealment will cost you firepower and/or area coverage and exposed turrets are much easier to damage or destroy.
- If you want full 360 degree coverage on all axes, you need a floating turret, or as I call them "orbit cannons". If built right, they will aim and fire at anything in any direction and will not be blocked by parts of your parent structure. These are fun to play with but for any substantial firepower, you'll need to build big and mount them on a capital ship, a station or a planet.
Whichever method you use, it is wise to set up a wireless remote to toggle the AI on your turrets on and off. Otherwise, you may find yourself unintentionally triggering war declarations when your turrets shoot nearby friendlies/neutrals.
Also, if you want your AI to fire the turrets, turn off "remote control". This will allow you to concentrate on flying and let your guns do their jobs.