Welcome to QuickBooks Community. Allow me to help you in setting up a user.
QuickBooks Online has different user types and access rights. However, we're unable to create one with a bank reconciliation access only. You'll want to check this link so you can choose the perfect user role: User roles and access rights in QuickBooks Online.
Then, you can follow these steps on how to invite them:
From the Gear icon, select Manage users.
Select Add user. Choose a user type, then select Next
Follow the on-screen steps.
Enter the user’s name and email address. Then select Save.
Once done, they'll receive an email invitation and they need to accept it.
I'd like to share something about the audit log. You can use this to review the changes and things your users made on the account. For more details, check this link: Use the audit log in QuickBooks Online.
Post again here if you need anything else. Wishing you all the best!