One checkbox will protect a whole workload in Microsoft 365 Backup. What it bills is not what you see in the usage report
Full Workload Backup reaches general availability from mid-September: one policy per workload protecting every SharePoint site, or every OneDrive account, or every mailbox, including the ones created later. List price is $0.15 per GB per month, applied to a base that adds in the second-stage recycle bin and online archives. Microsoft warns that its own usage report includes neither, "and is thus incomplete", and offers a calculator that does ask for them. The problem is that the report is what everybody looks at.