Bob only needs to update project schemes in your Jira site.

The correct product access configuration for Bob is Jira Administration with Product admin role and Jira Software with User role. This will allow Bob to update project schemes in Jira Software, as well as other project settings, without using a license. The Product admin role for Jira Administration grants access to the Jira Administration product, which is aseparate product from Jira Software that does not consume a license. The User role for Jira Software grants access to the Jira Software product, which does consume a license, but is necessary for Bob to view and edit project schemes12

References = Manage product access, Jira Administration overview