Importance of an Offer Letter
Per the HR policy of every organization, the selected candidate is offered an offer letter where everything is mentioned, such as salary, job location, job responsibilities, reporting manager, leaves, code of conduct, resignation procedure, etc. Once the candidate accepts it, all the details are clarified. In your case, you should request it so that all the above details are clear. If the company hesitates to provide it, I suggest looking for another professional company.
Best of luck...