It's important to understand the difference between visual procedures, visual flight rules, and visual meterological conditions.
Airliners always operate under instrument rules because it guarantees them ATC services, and because it's a requirement for proceeding into instrument meterological conditions (IMC). Also, higher airliner flight level altitudes are reserved for planes on instrument flight plans.
In instrument meterological conditions, only instrument procedures are used. But in visual meterological conditions (VMC), airplanes operating under instrument flight rules (i.e., those following instrument flight plans) are often required to perform visual procedures like flying visual approaches, or maintaining visual separation from other airplanes.