Here some example about testing some (not so good) 455kHz IF filter.
For this kind of filter, dynamic range with
Channel Gain Hold mode is well enough.
Horizontal scale 5kHz/div
CH4 is just only for display noise level (it also increase sweep time)
ALC Off (Channel Gain: Hold)
It can see that dynamic range is enough for this (presumably CFWLB455KJFA-B0 or clone) ("W55I-1")
All same as in previous image except now ALC On (Channel Gain: Auto)
As can see dynamic range is now much more and this "toy" filter do not need at all this whole dynamic range what is now available. So.. turn ALC Off and save time (but first set manually right V/div).
ETA: Addendum.
Here we go to (below 0dBm) dynamic range limits. So do not believe it can do some magics and miracles, all have limits in real world. Still result is amazing in this device class. Just normal oscilloscope Bode Plot.
the picture tells...