Let me share an idea about a Trust account where you can keep a record of your client's trust fund.
In QuickBooks Online, you can create a Trust account where you can record trust funds. However, this is for recording purposes only. You don't need to have a different subscription. But if you're referring to a Trust account where there is money movement, I'd recommend you consult an accountant to help you.
Here's how you can create an account:
Go to Settings ⚙ and select Chart of Accounts.
From the Account Type ▼ dropdown, choose an account type.