Hi there,
Yes, you can if your transactions from QBDT were also imported to QuickBooks Online, since QBO will only include data after the migration. It doesn't connect with your previous QBDT account data.
If transactional data (like journal entries, invoices, or account balances from previous periods) were imported into QBO during migration, it's available for your Trial Balance report. If not, and you need a complete Trial Balance for time periods prior to switching to QBO, consider manually entering or importing prior transactional data into QBO.
Let me know if you have additional concerns in QBO. We're always ready to assist.