I don't think so, but nowadays Zotero File Storage subscriptions automatically adjust their expiration data based on the cost of the selected storage tier and the remaining prorated balance.

So you could pay for a higher storage tier than you need and then select a lower tier. E.g. if you pay $60 for a one-year subscription to the 6 GB plan and then immediately switch to the 2 GB plan ($20/year), your expiration date should change from 1 to 3 years in the future.

Is there a "contact" or "help" to ask this question to Zotero folks? I have the money right now (it will go away later) to pay for multiple years, but I can't figure out a way to do that.