As a freelancer, you choose the gigs and the hourly rate you like to work for. Have you seen a nice gig, but don't agree with the hourly rate? Then you can make a counter-offer. You do this in the app while signing up for a gig. 

Are there few responses to the gig? Or do you have a very good motivation and rating? Then your counter-offer will definitely stand a chance. We see that a counter-offer is accepted in about 20% of the cases.