ITIL 4 is the most widely used framework for IT service management. A certified consultant has been examined on its concepts: the service value system, the guiding principles, and the practices behind incident, request, problem and change management, service levels and the configuration management database (CMDB).
On a project, that means your process owners, your service desk and your consultant use the same words for the same things from the first workshop. Nobody spends the first weeks agreeing on what a problem is or when a change needs approval.
A certificate does not replace field experience, and we do not present it that way. Our consultants combine ITIL v4 with the 180 ITSM implementations and 40+ migrations SMC Consulting has delivered, and they adapt the framework to your organisation instead of reciting it.