Recruting Agencies?

Nope. Most of the time they mention companies that don't accept third party sourcing.

C-level ? Want to hear more : ignore.

Some companies who don’t have recruiting team, do hire outside companies to find candidates. Soon in the process you will realize if they are reliable

Not worth it unless you know the recruiter personally. The randos on LinkedIn often use tactics like they have a position for some high amount of TC to get you to come in and then they just try to pitch you other opportunities. Feels like talking to a used car salesman.