"Can I be honest?"
Makes people wonder: “…were you not being honest before?”
You might actually intend to be: blunt, candid, thorough, discreet, vulnerable, unfiltered, open, inviting, challenging, or any number of other intentions.
Words matter. Triply so for leaders.
This is an important one! A dramatic pause before saying something kind of does the same thing, but I like your alternate wording suggestions.