Any QuickBooks Online (QBO) user that has the Vendors permission enabled can create BILLS and BILL PAYMENTS in QBO.
By default this would include any QBO users who are the following user types:
Standard user with full access
Permission can be removed by unchecking the Vendors checkbox in QBO
NOTE: It is not possible to give a QBO user access to BILLS and no access to BILL PAYMENTS. If you need this level of permissions please Give feedback to the QuickBooks Team or consider upgrading to QuickBooks Online Advanced which includes the ability to create custom permission settings.