No, you cannot have the ID of the record if it is not created yet.

I don't know why you need the ID but if you want to access the value of the other fields, you can use onchange method to get the value of the fields and do some operations.

@api.onchange('partner_id')
def onchange_partner(self):
    self.partner_id
    self.my_field1
    self.my_field2
    # You can access the value of the fields in the onchange like this