Which is a key element of the 'think and work holistically' guiding principle?

No service, practice, process, department, or supplier stands alone. The outputs that the organization delivers to itself, its customers, and other stakeholders will suffer unless it works in an integrated way to handle its activities as a whole, rather than as separate parts.

Taking a holistic approach to service management includes establishing an understanding of how all the parts of an organization work together in an integrated way (remember the four dimensions of service management?), including having an end-to-end visibility of how demand is captured and translated into outcomes. In a complex system, the alteration of one element can impact others and, where possible, these impacts need to be identified, analysed and planned for.

To apply this principle successfully, consider this advice:

Recognize the complexity of the systems

Collaboration is key to thinking and working holistically

Where possible, look for patterns in the needs of and interactions between system elements

Automation can facilitate working holistically

https://www.bmc.com/blogs/itil-guiding-principles/