It all depends on how you arrived and what you want to see. Traveling by car includes tolls, gas and parking. For example, tolls costs from Zagreb to Osijek amount to around 15 euros. Parking prices in the city depend on the parking zone, and range from 0.27 € to 0.53 € per hour, and up to 2 € for the whole day.
If you are coming to Croatia by plane, count on the costs of the plane ticket to Zagreb as well as transfers to and from the city. The cheapest way to get to the golden cornfields of Slavonia and Baranja is by public transport, i.e. by bus or train, which run every day at a price of 15 €, including a one-way ticket, without a luggage surcharge of approximately 1 €.
When you get to the city, it's all up to you. You will quickly realize that everything is within reach and that you will not have to think too much about how to move around the city. If you want to discover Osijek outside the cultural center of the city, consider renting a regular or electric city bike at a price of 3.99 € for a half-hour ride or rent a bike for the whole day at a price of 25 €, there is also the option of renting a Bolt electric scooter, via a Bolt Bolt application.