Well, Yes and No!
Both headphones, as far as I know, use the same drivers!
Here is LCD-X
Here is LCD-XC
And here is one, superimposed on the other, allowing for treble level:

The faded curve is LCD-X, the solid curve is XC.
It is a matter of point of view!
From the superimposed graph, you can see that:
1- Both headphones have the same FR from about 1.8kHz upwards.
2- The XC, being a closed back, has all outputs below 1.8kHz, muted a bit.
OR
3- The X being an open back has all lower frequencies boosted! This is because there is no back pressure on the diaphragms.
This makes the headphones sound warmer,
OR makes the XC sound brighter, depending on your view-point.
I personally did a simple Mod. on my LCD-XC (
https://www.audiosciencereview.com/...eze-lcd-xc-21-effects-of-small-venting.42829/
From my measurements, after allowing small venting to occur on the XC, you get this:
Just look at the curve below 300Hz.
As I reduced the back pressure from XC diaphragms, in small steps, it changed the bass FR curve.
Here is a zoomed version of the affected area.
At the end of the day, either, the X is too warm, or the XC is too bright, take your pick.
But since both headphones have almost no DISTORTION to speak of, EQ to you heart's desire, just make sure you don't run out of gain.
Distortion? what distortion!