The smallest ships I build recently are 5 blocks heigh, 9 blocks wide and 15 blocks long.
Most of the time, they are 7-9 blocks heigh, 11-13 blocks wide and 18-30 blocks long.
Thus, first I'll build a shipyard with dimensions 15x 11y 23z to 32x 16y 64z and would upscale from that.
My hangars have that size. Shuttle hangars garanteue the smaller as inner size and station hangars the bigger box as inner size.
Special hangars may build around the docked ships size, garanteue the smaller, eventually the bigger on biggest diameters within that shape.
My Tier2-ships (T0 is drones and T1 is for 1-4 crew members) do include such a hangar for an emergency shuttle and have 2 reactors, thus are often 2x2x2 in size with only 3-5x the amount of usable crew interior (4-20 crew members).
Their shipyard would be just 2x scaled. Smaller ones for specific designs and maxed-out ones between 30x 22y 46z and 64x 32y 128z for dedicated stations where you have space in abundandence.
My Tier3-Ships and shipyards are only theoretically now.
I plan to include them on every dedicated shipyard station of factions with more than 1 person when I will play online again.
Tier4-Ships and shipyards would be upscaled 8x from the smallest one and always maxed-out.
They must garanteue that a box of 256x 128y and 512z fits into them, but probably they are built for 384 xy and 512z to allow more freedom in shapes. The point is, that some factions will only have one of these at their home-base and all common tasks can be solved with shared ships buildable in this one shipyard.
Tier5: Everything above is experimental and not factory-supported by me.
Every combat ship above would be build without shipyards and modularly dock Tier4-sized crew spaces, armor plates, weapons and shield generators on a Tier4-sized stick. These ships may slab 3 T4 ships together and let the player build reactors in a provided hollow corridor within these 3.
Or there is a server-wide, admin-spawned shipyard or some admin-spawning and control over such huge ships. Perhaps some factions build such km-long shipyards, but not having these shipyards is a good way to implement ship-size restrictions on a server for mass-spawned ships.
Tier6: Ofcourse everyone can manually build bigger, but peoples don't need a 2km long flagship when most ohter peoples build ships with 1/30 volume in Standard-Tier4 shipyards of a half-km size.