At the moment, QuickBooks Online (QBO) doesn't support printing bills. But, there's a workaround that you can use to access your vendor's bills. You can run and customize the Transactions List by Vendor report. Here are the steps to do it:
In the left menu, click Reports.
On the search bar, type Transactions List by Vendor.
Additionally, I have also included a couple of articles that can guide you on managing your bills in QBO. They include steps on how to pay and email the transaction: