Hi @lszabo,
You’ll see the checkbox if you are refunding a paid order:

Link to image: https://d.pr/i/zyPNUp
If your workflow is such that you are changing a paid order to On Hold and editing line items, I believe you should still see inventory correctly adjusted. There is no checkbox in this case.
I did some tests on this and inventory was adjusted automatically based on my line item edits for a previously paid, status changed On Hold order:

Link to image: https://d.pr/i/0ibicd
Please note we also have an open issue with regards to inventory and line item editing and you may need to adjust your workflows accordingly. You can see more information on that here: https://github.com/woocommerce/woocommerce/issues/27504
Could you let us know if you are still seeing this issue? If so, please give us the exact steps you are using when you are making these order edits, e.g. are the orders paid, are you changing status, how is inventory set / managed for the product?
Thanks for your help!