What a takeover is
A social media takeover means temporarily handing control of an account to someone else (a guest creator, an employee, an event speaker) for a defined period, usually a single day or event. The format works because the voice changes for that window, which gives an established audience a reason to pay closer attention than usual.
Set real boundaries in advance, not mid-takeover
What topics are off-limits, how many posts are expected, and who has final say if something questionable comes up are all worth agreeing on before the takeover starts. A takeover happening in real time leaves little room to intervene if something goes wrong partway through.
Announce it clearly, both before and during
An audience should know a takeover is happening and who is posting. Announce it ahead of time to build anticipation, and reflect it in the content itself with a real introduction from the guest, so nobody is confused by the sudden change in voice.