In my first school, there was a very intimidating meeting where staff were threatened with Gross Misconduct if their FB profile wasn't completely locked down and told that 'we will be checking on you all'. Naturally, I got straight on there to doublecheck and block every possible permutation - it took all of ten seconds to find the head's personal FB, twenty to find all of SLT and probably another five minutes to find a potential conflict of interest in a recruitment decision and also a very niche 'interest' on the part of somebody else. All from the people making the threats.
I was already locked down, but I made absolutely certain that there was nothing to see that could cause concern, just in case a 'friend of a friend' slipped through the net or someone I knew decided to adopt a Scorched Earth principle when posting and I became tainted by association.
In the process, I found that an ex Governor had clearly used the burner email address I had set up for a whistleblowing disclosure through the Twitter 'people you might know' function and followed a defunct Twitter account I'd opened with it. Which prove to me I was absolutely right in doing that.
These days, they would get the details of a completely inoffensive set of accounts - music (and not 'controversial' bands/genres), animals & wildlife, Gardeners' World, The Archers, Radio 3, etc, and would therefore see I exist online, but not that I'd be in any way harmful or detrimental to their organisational aims. If the lack of updates were queried, I'd be able to say quite honestly that FB/Twitter/IG do not form a significant part of my life.