Yes, you can directly upgrade to Version 21H2 via ISO file and that's an offline upgrade usually.
Refer this step-by-step guide:
Let us know if this helps!
Note: Included link in this reply refers to blog post by a trusted Microsoft MVP.
I want to update some laptops that are running on some older builds to the newest 21H2.
Is there any offline solution or an ISO i can download and install offline from usb?