Starfield Skills -> Stealth Skills
Stealth is a skill in Starfield located in the Physical Skill tree that helps players avoid detection while sneaking and also improves sneak attack damage with ranged and melee weapons.
Stealth Skill Description
For a combatant who values discretion above all else, the ability to approach a target while undetected and kill with a silenced weapon is as terrifying as it is effective.

Stealth Skill Ranks
Rank 1
Adds a Stealth Meter. You are 25% more difficult to detect when sneaking. Suppressed weapons do an additional 5% sneak attack Damage.
Rank 2
Upgrades the Stealth Meter. You are 50% more difficult to detect when sneaking. Suppressed weapons do an additional 10% sneak attack Damage.
Rank 3
You are 75% more difficult to detect when sneaking. Suppressed weapons do an additional 15% sneak attack Damage.
Rank 4
You are 100% more difficult to detect when sneaking. Suppressed weapons do an additional 20% sneak attack Damage. Doors you interact with while in stealth no longer alert enemies.