Yes you can and I do use acorns for round ups and investing but I don’t use acorns to pay bills but yes you can pay bills. I have links below that can show you how to pay bills with acorns:
https://www.acorns.com/support/spend/can-i-set-up-bill-pay-/
https://support.acorns.com/hc/en-us/articles/360052529114-Can-I-set-up-Bill-Pay-