Good to have you here in the Community, raihananazri-gma.
Let me share some insights about creating and managing classes in QuickBooks Online. Usage limits depend on your subscription. These limits apply to how many billable users, a chart of accounts, classes, locations you can add to QBO.
I have here resources you can read for additional reference and guide about class tracking feature in QBO:
Feel free to comment below if you need anything else. I'll be sure to get back to you.