Amazon Author Central provides a free author profile page at author.amazon.com that aggregates all your books, an author biography, a photo and optionally a blog feed. Every author should set this up immediately after publication. It is where readers go when they want to know more about you after reading your book.
Goodreads author profiles are free and serve a similar function for the reader community that uses the platform actively. Social media profiles on Instagram, TikTok (BookTok) and Facebook reach author audiences directly without website infrastructure.
For most debut authors, Amazon Author Central plus social media presence provides sufficient online footprint to support the first book launch.
An author website becomes valuable when: you have multiple books and want a central discovery point for new readers, you are building an email list to market directly to your audience, you speak professionally or consult and the book is a credibility tool, you are creating related products (courses, coaching, membership) connected to the book's topic, or you want to sell books directly at a higher margin than Amazon allows.
A business book author whose goal is speaking engagements needs a website because speaking bureaus and event organisers look up speakers before booking. A romance novelist publishing a 10-book series benefits from a website because readers want to follow an author they love. A debut fiction author publishing book 1 does not necessarily need a website before it is clear whether there will be a book 2.
Publish the book first. Set up Amazon Author Central immediately. Build social media presence in parallel. Add a website when: you have something to put on it beyond a single book, you have clarity about your author brand, and you are generating enough traffic from other channels that a website would capture and convert it. Building a website before publishing the book is the wrong order of operations for almost every debut author.