Decompose "Two Weeks"
Work from the brief alone. Write what you would produce — actors, requirements, data, a first slice, your unknowns — before opening anything below it; the exercise stops working if you read the reality first.
An engineer estimates the store's returns-and-refunds feature at "two weeks" and the roadmap now says so. Decompose it, estimate each piece as best / likely / worst, identify the piece whose unfamiliarity dominates the range, schedule the spike that narrows it, and give the product manager one usable number with what is attached to it.
Your attempt
Nothing here is checked. It exists so that the reveal below is a comparison rather than a reading.
Doubling the estimate to be safe. Four weeks has no more information in it than two; the refund piece is still unexamined, the roadmap now carries a padded number that will be spent, and the day the spike would have taken is never scheduled because the padding made it feel unnecessary.
Read this even if you are confident. It is here rather than behind a button because it is the move most people actually make, it produces things that look like a project, and its cost arrives when the first hard requirement has nowhere to go.