Starfield is already getting attention from the modding community despite the game not having the official mod tools released.

Starfield has been out for a little over two weeks now, and despite the lack of official modding tools, modders are rolling out mods in various forms, with one being the implementation of Stormtroopers. Now, we are starting to see mods surface that fix some of the most annoying aspects in Starfield. For instance, players have always wanted to be able to create a ship without size limitations. Vanilla Starfield ship construction is limited to 40 meters long and wide, which isn't enough if a player wants to build any large ship from Star Wars.
Thanks to NexusMods user AccursedPrism, players can now enjoy Starfield ship creation without a size limit, as the new mod overrides the default limitation of 40 meters and adds the following options - 60 meters, 80 meters, and 4/5 kilometers. The sizes below 100 meters are considered to be "safe", which indicates minimal or hardly any performance issues or in-game bugs. However, 4/5 kilometers will likely have a massive impact on performance/cause bugs. Check out this mod here.
Additionally, modder MedievalAI has released a mod that increases the total number of ownable ships from the default 10 to 50. Check out this mod here.

Height Randomizer
Another mod to point out is the new height variation mod that changes the height of NPCs, which adds a new level of realism to regions such as New Atlantis. This mod is called Height Randomizer and was created by carxt. Check out this mod here.
The mods don't stop there, as ArmoredTroll has developed the "NPCs Use Ammo" mod, which does what it says in the title - forces NPCs to use ammo as opposed to vanilla Starfield, where NPCs have infinite ammo. This mod will force NPCs to scavenge for ammo from dead bodies, crates, containers, and anywhere else they can in order to keep using their weapon. Check out the mod here.
Mods such as the ones mentioned above are just the start of what will undoubtedly be a widespread and innovative mod space. However, it should be noted that since the official modding tools won't be released by Bethesda until sometime next year, many of these mods may cause performance issues or result in bugs popping up in random spots during gameplay. The severity of the mod typically coincides with the likelihood of bugs or performance issues presenting themselves.
For example, if you build a 2-kilometer by 2-kilometer ship, you are probably going to run into some problems.