Even if you’re sure you want this job, you should not accept it on the spot. Rather you should a couple of days before deciding to accept a position. It will help you to decide if you have any questions, concerns, or requests. It allows you time to negotiate. Here are some benefits of not accepting a job offer on spot.
Create good impression
When you request some time to think about the offer, it may create a good impression on the hiring managers. Employers will think more highly of you. They can realize you value the necessity of review. So, asking for time to review a job offer before accepting is always a professional way to proceed.

Allow you time to review
It is not professional to ask questions to the employer about salary or other benefits after accepting the job. It is better to review all the information carefully make sure you have all the required information like starting date, job responsibilities, job title before accepting a job.

Have time to negotiate
When you have time to review, you’ll also be able to decide what to negotiate. You can negotiate the base salary and other benefits like equity, health insurance plan, and much more. If everything seems okay, you can decide to accept the offer.

Finish interview with other company
If you have the chance to attend multiple interviews, you should ask for time to review the offer letter. It will allow you to finish interviewing with other employers if required.