Hi there, Jonathan.
Yes, you can still use the QuickBooks Online VAT feature if you're only purpose is to track your taxes and not to file or reclaim them. However, please take note that can only charge VAT if your business is registered for VAT.
Also, the program does not have a specific report intended for VAT threshold calculation. QuickBooks follows the guideline that VAT applies to you as soon as your sales of VAT-taxable goods and services exceeds £85,000.
Although, you can run the No VAT transactions report to see all the transactions that does not have VAT applied to them. Just go to the Reports menu and type in the name of the report in th Search bar. Let me also share these articles with you about tracking VAT in QuickBooks Online:
I would also recommend reaching out to your accountant for further advice on this matter.
The Community is always here if you need anything else.