There's definitely a "glazing" axis/dimension in some of them (cough, GPT-4o), presumably trained into them via many users giving a "thumbs up" to the things that make them feel better about themselves. That dimension doesn't always correlate well with truthfulness.
If that's the case, it's not implausible that that dimension can be accessed in a relatively straightforward way by asking for more or less of it.
If that's the case, it's not implausible that that dimension can be accessed in a relatively straightforward way by asking for more or less of it.