Yes, you can include both free tickets and paid tickets in the same event.
All you need to do is complete the procedure for the first type of ticket (you can start with any of the ticket types), and then choose “add another ticket” to insert the second type of ticket into the same event.
You can insert as many ticket types as you want, and set specific properties to each type, such as the beginning and the end date of the availability, available quantity, discount codes, additional information, related data collection forms etc.