Hi, kiran4.
I can share some information regarding extending the accounting period in QuickBooks Online.
You can have extended reports. However, extending the accounting period in QuickBooks isn't currently unavailable. A fiscal reporting period is only up to 13 months.
Also, I'd suggest getting in touch with your accountant. Your accountant can provide more expert advise regarding an accounting perspective.
Please know that you can always visit our Help Articles page for QuickBooks Online in case you need some reference for your future tasks.
Feel free to drop me a reply below if you have any other concerns. I'll be around to help you out.