Hi magdalene.teoh@c,
Thanks for reaching out here. Welcome! QuickBooks Online automatically creates the associated accounts, when the Sales Tax feature is turned on. Sales tax will automatically be calculated when creating your transactions, to ensure accurate filings. I'd be happy to provide some insight here!
Once you've reviewed and marked your sales tax as Filed, a journal entry will be automatically created for the the sales tax owing for that period. The journal entry records the date as the End date of the filing period. To learn more about the default and special accounts in your chart of accounts, click here.
Feel free to reach back out with other questions. We would be glad to help!