Hi,
In Odoo 19, there’s no built-in approval step for 
physical inventory updates, but you can achieve it through access rights
 or customization. The simplest method is to restrict the Apply
 button to inventory managers only. With this setup, employees can enter
 counts and save them, but only managers can finalize the update.
For a smoother process, you can introduce a custom approval workflow. This involves adding an intermediate state such as “To Approve”,
 where employees submit counts for review. Managers can then see pending
 adjustments and confirm them, which updates the stock. This approach 
requires a small customization to extend the inventory adjustment model 
and adjust button visibility based on user roles.
As alternatives, you can use activities to notify 
managers for review, or, if you have Odoo Enterprise with Studio,add an 
approval field that only managers can edit, making the Apply button 
conditional on that approval. In short, you can either restrict 
validation to managers or add a formal approval step with a 
customization or Studio configuration.
Hope it helps