What will you be doing to grow their account? Answer yourself and this is what you will tell them.
IMO It is OK the use selling lines like those you metioned, but it is very important to keep full clarity with the client. You don’t want the to discover you’re doing F/UF in retrospect.
I always make sure the client fully understands the service he is buying.
This way you’ll avoid scenarios where the client is surprised from the result compared to what he thought he will be given.
That’s exactly how I explain it in the sales pitch.
I straight up tell them I f/uf as part of my process after they’re signed up as part of my “things to expect”. I then describe how followings will go up, they’ll get random dms, I mute the accounts, blah blah so there’s no surprises for them.
Never had a client complain, in fact I’m usually praised for the communication.