Yes, a business plan is nearly always required when seeking financing. Business plans fall into three common categories: those used for funding, those used for strategy, and those used for both fundraising and strategy.
Regardless of their business model, many business owners use their plans to raise bank loans to grow. The funding allows them to acquire additional business resources and improve their financial health. New business owners often seek bank loans as well as funding from angel investors and/or friends and family. Importantly, regardless of the source of funding you desire, you must make your business plan stand out from the others by showing compelling reasons why you will be successful.