Polished Chapter Book Query Letter

I have just finished an adventure-packed chapter book for readers aged 8-10 and I am ready to approach literary agents. What I need is a single, professional yet attractive query letter that sells both my story and my author brand in roughly 300 words... (Budget: ₹600 - ₹650 INR, Jobs: Article Writing, Book Writing, Content Writing, Copywriting, Creative Writing, Editing, Ghostwriting, Proofreading)