Those two numbers you are asking about ("true rate" or the abstraction), for the recent past, pretty much work out to the same value.
The CPI excludes some volatile categories, but it's not a trick, in this case.
The tactic of bringing up that the CPI excludes some categories, and implying that if it did include them, it would show more inflation than what it does (including the pretty significant spike in 2022)... that actually is a trick, actually a pretty subtle and clever one. To make people think the economy is getting worse, when it's getting better.
Edit: I made a top level comment with the guidebook to some of the other tricks