When using this action, your identity will follow the lead profile. LinkedIn will notify your lead that you follow his profile.
It is recommended you use this action :
Upstream: For social warming, so that your lead already knows who you are before sending your first message.
During a campaign: While sending DMs and Voices - to give the impression that a human is following up.
Like a follow-up that's not just another message - the notification will serve as a reminder to your prospect and help them remember you.