Yes, it is advised that you convert a small sum of money into Indonesian Rupiah prior to your arrival. Small local warungs, markets, and taxis only take IDR and exclusively deal in cash. On the other hand, you can also exchange money in Bali at a better rate than you would back home. All major currencies are accepted by Bali's money changers, so you normally don't need to bring extra cash.
Even though credit cards are generally accepted, travelers should have some cash on hand in case you need it for minor transactions or at establishments that might not take them. Furthermore, having both cash and credit cards on hand guarantees that you have fallback options in the event that one of the methods is not accepted or if there are ATM malfunctions.
The exchange rate of Indonesian currency depends on which nationality you are, you can refer below:
In conclusion, travelers should bring some cash before traveling to Indonesia. By this way, you do not have to locate a bank or currency exchange as soon as you get there and gives you time to compare rates.