Scheduling an offer call?

So I am ecstatic but I am also seeking guidance, so thats why Im here. I went through 3 rounds interviews with a great company and everything seemed pretty standard. First round was screening with HR,

So I am ecstatic but I am also seeking guidance, so thats why Im here. I went through 3 rounds interviews with a great company and everything seemed pretty standard. First round was screening with HR, second round was with a set of supervisors and the third was with my direct supervisors. Then they asked for references. After they spoke with my references they offered me the job, but they asked to schedule a virtual call to extend the offer. Any other”big boy” job Ive gotten they either just called and told me I got the job over the phone and to expect an offer letter or sent me an offer letter through email. Ive scheduled a call for a week out. Nothings wrong with this, it’s just nothing Im used to. Is there anything I should be preparing for in this call? Should I prepare counters? Has anyone had experience with this and what do you think I should expect? Insight?