If your business plan is for the purpose of raising money, then funding sources will want to see 3-5 years of financial projections as well as market information that will support those numbers. I would need to know what your definition of "business plan" is.
If you look up typical business plan templates, you can find the items that should be in a business plan; however, 20 and 30 page business plans rarely get read. I suggest no more than 10-12 pages of what funders want to know to lend or invest money.
If you would like assistance on this, feel free to contact me as I have prepared many business plans and pitch decks.
Best of luck,