I'm not sure why anyone would try that considering that Elear and Elex exist.
Because the Elear and the Elex suck.
Seriously now, despite sporting a name that starts with "El" the Elegia has more in common with the Clear OG; same driver, same magnet, which are different from Elear and Elex. This can incite some enterprising audiophiles to believe they can transform their Elegia into a Clear for little investment.
Personally, I don't think that would work. I am a lifelong collector of headphones; I have all the "muscular" type Focals from Elex to Utopia, except for the Celestee and the sponsored models. They all exhibit their very own personality, some I like, some I don't. I like the Clear, I don't like the Elegia OOB. I seriously doubt the latter could be made to sound like the Clear, but one is welcome to share their musings about it
On a side note, having the same driver as the Clear is the major reason why Focal designed the Elegia as a semi-closed unit. A compromise to avoid having to research a proper driver otherwise, so Focal wouldn't have been able to MSRP under $1,000 without sustaining a loss, considering that they had expended a lot of resources on the Elegia's "vented labyrinth" cup design. I'd wish they had spent as much on re-tuning the driver. I suspect it was left exactly as tuned as for the Clear OG, hence the less-than-impressive SQ of the unit's OOB experience. One can't expect much from a driver that was tuned for an open-back to perform well in a closed-back without user tweaking. Also, Elegia's pads are horrific.