I think I agree with what most of the answers state - there are an amazing ( and confusing) lot of templates available online - both free and paid. And yes, almost none of them will be a perfect fit for your business.
That said, the templates can be useful for formatting your plan, and more importantly, your thoughts. You can find areas you may have forgotten or glossed over, and bring them into your plan.
I am particularly partial to a template - i will more likely prefer to call it a tool - the lean canvas. This can be a starting point for plan - yes, definitely not a template for the plan.
What I like about it is, that it focuses on the key aspects of the business plan for any kind of business, and forces you to think about each of them and their linkages, and have it all within an A4 size sheet of paper. The details may need to be developed off the canvas, but the key points - the inputs for business, the outputs and the metrics for them are all on one sheet.
The product design and the revenue model will also need to be developed separately, but they are usually not forgotten,and definitely need and additional eye to check.
But the lean canvas focuses on the basics and ensures you do not miss out the essentials.
Finally, as with every ready to use resource out there, the templates and tools can only be signposts to your way,you have to make the journey yourself.