c-style-variables-are-local-p

c-style-variables-are-local-p is a variable defined in `cc-vars.el'.
Its value is

t

• This variable is safe as a file local variable if its value
  satisfies the predicate `booleanp'.

Documentation:
*Whether style variables should be buffer local by default.
If non-nil, then all indentation style related variables will be made
buffer local by default. If nil, they will remain global. Variables
are made buffer local when this file is loaded, and once buffer
localized, they cannot be made global again.

This variable must be set appropriately before CC Mode is loaded.

The list of variables to buffer localize are:
c-basic-offset
c-comment-only-line-offset
c-indent-comment-alist
c-indent-comments-syntactically-p
c-block-comment-prefix
c-comment-prefix-regexp
c-doc-comment-style
c-cleanup-list
c-hanging-braces-alist
c-hanging-colons-alist
c-hanging-semi&comma-criteria
c-backslash-column
c-backslash-max-column
c-label-minimum-indentation
c-offsets-alist
c-special-indent-hook
c-indentation-style

You can customize this variable.