Fixtures can be quick swaps or licensed work depending on what they connect to. Describing the fixture and the existing connection is the fastest way to an accurate answer.
Name the fixture and its location
Say what is being installed: a ceiling light, a faucet, a towel bar, a mailbox or a smart device. Give the room and whether it replaces an existing fixture or goes somewhere new.
Describe the existing connection
Note the existing wiring, plumbing, mounting box or wall type. A fixture that swaps into an existing connection is usually simpler than one that needs new wiring, plumbing or blocking.
Know when a license is required
In California, electrical and plumbing work generally requires a licensed contractor. A handyman can often swap a like-for-like fixture, but new wiring, new circuits, gas or water lines are not handyman work. Ask the provider to confirm scope.