The scale of your music event is a big consideration here. Bands who are just starting out will probably be happy to play in pubs and clubs. The small gigs at the start of a career are a rite of passage for musicians.
Don’t spend a fortune on booking performers who are expensive if you’re starting on a small scale.
On the other hand, think about the band or bands bringing fans. At least one of the bands on your lineup should be a draw and bring along a lot of their own fans. Hiring three unknown bands for a venue with a 1,000-person capacity is a recipe for disaster.
Finding bands requires some legwork. This is especially true if you do not have any in mind.
A search on Google will yield results such as function and wedding bands. These are costly and will play cover versions of songs. It’s probably not what you have in mind for your music event.