I get criticised occasionally for long and detailed posts that some readers complain treat them like beginners, but sadly if I don't I get comments such as this in reply
Data Loss is something you prevent; you enforce controls to prevent data
leakage, DLP can be a programme, but , I find very difficult to support
with a policy.
Does one have visions of chasing escaping data over the net with a three-ring binder labelled "Policy"?
Let me try again.
Policy comes first.
Without policy giving direction, purpose and justification, supplying the basis for measurement, quality and applicability (never mind issues such as configuration) then you are working on an ad-hoc basis.