Can I use both online and desktop for one company especially some bookkeepers are doing remote work?

Yes, you're right @abbiebperez-gmai, that it's possible to grant access to your bookkeepers in both QuickBooks Online and Desktop.

In QuickBooks Online you can just add a bookkeeper user. Let me show you how:

1. Sign in to a QuickBooks Online account as a primary admin.
2. Click on the Gear icon, then hit Manage Users.
3. Once routed to the Manage Users page, choose  Accountants.
4. You can then enter your accountant’s email address, then select Invite.

For QuickBooks Desktop you can host your company file in order for your bookkeeper to access remotely. Otherwise, if you are not comfortable with hosting your company file, you can just add another user license for your bookkeeper to have their own access, be it on their own laptop or computer remotely.

Moreover, you can check these resourceful articles for future reference about managing your bookkeeper's access:

• Troubleshoot Accountant File Transfer service issues.
• Add and manage users in QuickBooks Online.

I'm all ears if you need help handling remote access for your bookkeeper in QuickBooks. Please don't hesitate to reach out. Stay safe, and have a good one!