how can I formulate an engineering project mangement scope of work, considering managing multiple contractors on an SPM subsea pipeline project up to onshore terminal facilities installations?
Do you have your technical requirement defined? If so, simplistically you build your scope of work around the effort required to meet these.
As to template, there are sources of generic template. Some of them have been mentioned on this site before - do a search. Have you done a google/internet search yet?
You didn't answer the question about if your employer has previous examples you can look at, they might even have their own template hidden away in some procedure. Have you asked your colleagues/supervisor?
KENAT, probably the least qualified checker you'll ever meet...