Originally Posted by SoSmellyAir

There is some ambiguity here because "hood" can refer to two things. If by "hood" you mean the entire STI structure with the underlying shift and brake mechanisms (Shimano Dura-Ace ST-R9100 11-Speed STI Shifters | Competitive Cyclist) rather than just the cover (Shimano STI Lever Hoods | Competitive Cyclist), then yes, a "hood" is generally sold with a lever as an integrated unit.

Originally Posted by Ironfish653

You need to give a few more details about what you’re trying to do.
On a modern (1990s or newer) bike, drop-bar brake levers, whether brake-only, or an integrated brake/shifter’STI’ unit, have a rubber cover/grip over the base/mounting hardware. This rubber cover is the Hood; it comes as a part of the lever assembly, and is usually specific to a particular make or model lever.

Being that it’s a rubber grip surface, the hoods are subject to wear and damage, so you can often buy replacement hoods to repair or refurbish lever assemblies without having to replace the entire mechanism.