Here is the full list of all 50 Starfield achievements. It takes around 100-120 hours to unlock all of the achievements on Windows.
Complete "The Hammer Falls"
Complete "Surgical Strike"
Complete "Legacy's End"
Complete "The Best There Is"
Reach Level 100
Eliminate 300 Creatures
Land on 100 Planets
Complete "Executive Level"
Complete "A Legacy Forged"
Complete "The Devils You Know"
Complete "Guilty Parties"
Eliminate 300 Human Enemies
Reach Level 50
Join the Crimson Fleet
Join Ryujin Industries
Join the UC Vanguard
Successfully Smuggle Contraband
Complete "One Giant Leap"
Collect 20 Quantum Essence
Complete "Unearthed"
Complete "Entangled"
Complete 30 Terminal or Misc. Missions
Reach Level 25
Complete "In Their Footsteps"
Reach Maximum Relationship Level with a Companion
Visit 20 Star Systems
Join the Freestar Rangers
Complete 30 Activities
Complete "High Price to Pay"
Complete "Further Into the Unknown"
Complete "All That Money Can Buy"
Modify a Ship
Complete "Into the Unknown"
Reach Level 10
Build an Outpost
Reach Level 5
Join Constellation
Enter Space for the First Time
Connect 5 Outposts with Cargo Links
Produce 500 Total Resources from Outposts
Visit all Star Systems
Gather 500 Organic Resources
Gather 500 Inorganic Resources
Bypass 50 Digital Locks
Access 50 Computers
Mod 50 Weapons
Craft 100 Items
Recruit 10 Separate Companions
Collect 10 Ships
Read 20 Skill Magazines