There's two things to consider, whether they'll find it and whether they're actually allowed to use it.
The PATH variable is what a users' shell will use to locate programs. /usr/bin will very probably be in the default PATH so users will find things in there by default. If they need to look in /usr/local/bin/ you may need to add that to the PATH. The PATH is adjusted in a variety of locations, see
How does the default PATH get set on RHEL?
Even if it's not in their PATH, they can still run programs by giving the full path themselves, i.e. running /usr/local/sbin/myprogramname
File permissions can also be used to allow or deny users from running programs they'd otherwise be able to access, but without knowing what you're trying to do this may be getting into too much detail.