Seagate has introduced the Exos M series, a range of enterprise-grade mechanical hard drives available in 30TB and 32TB capacities. The two models, the 30TB CMR ST30000NM004K and the 32TB SMR ST32000NM003K, each offer a minimum of 3TB per disk and use a standard 3.
These drives aren't for people who care how much they cost, they're for people who have a server with 16 drive bays and need to double the amount of storage they had in them.
(Enterprise gear is neat: it doesn't matter what it costs, someone will pay whatever you ask because someone somewhere desperately needs to replace 16tb drives with 32tb ones.)
In addition to needing to fit it into the gear you have on hand, you may also have limitations in rack space (the data center you're in may literally be full), or your power budget.