You can definitely hard book roles on a project, but I think your question is whether you can do this as a requisition manager, from within a requisition?
The requisition itself does not include details about the allocation status. You need to access the project pages -which you can do from the requisition if you have the appropriate rights over the project and role.
Solution 1
The following scenario assumes you have the following rights:
- Project - View for the project (enables you to update the project booking information)
- Resource - Hard Book for the role (enables you to change the booking status from Soft to Hard).
When you review a requisition for a role, there is a Requirement Name link on the General page. Clicking the link takes you to the Staff Member Properties page for the role, on the project.
From here, you have access to the Booking Status field which you can set to Hard.
Note: The above might not be an appropriate solution for data security reasons, because the Project - View right also gives access to the Properties, Team, Tasks, Processes, and Dashboard pages of the project, which might not be appropriate information for the requisition manager to have access to. However, additional rights are needed to access the Financial Plans, Chargebacks, Hierarchy, Audit Trail, and Collaboration, therefore these pages are protected.
Solution 2 (this needs to be investigated because I do not perform this type of work very often)
An alternative solution might be to create a new Boolean field for the Requisition object - for example Commitment Given. You could then define an auto-start process around this field being checked in the Requisition. The process could send an action item to someone who has the required Project - View and Hard Book rights? That way, the data-security is not an issue and this could even send the requisition owner a notification that the commitment is there, and also send you (the requisition manager) an action item that reminds you to fill the requisition by a certain date.