I've heard that the Elex is very close, like 90-95% of the OG Clear. I've also read that the Elex and Clear use the same earpads too; the Elex is an Elear with Clear pads based on what I've read.

So assuming you are listening at volumes that don't encounter the driver clipping issues that all Focals have (and the different driver on the Elex might make it more susceptible to clipping than the Clear), you are more likely to be able to EQ an Elex to sound just like a Clear, but again, you can't accurately do that with just a graph. The only way to you can accurately EQ the Elex to sound like a Clear is to have both headphones side by side, and EQ one to sound like the other by ear.

I've used and experimented with EQ a lot, and it's easy to destroy technicalities via EQ, but it's hard to improve technicalities with EQ. My experience is that technicalities are linked to relative levels of very narrow bands of frequencies throughout the audible range. "Correcting" small tonal problems via EQ also affects technicalities that are linked to those frequency ranges. EQ, even digital EQ, is not precise enough to accurately shape the needed frequencies without also messing up nearby frequencies. If you're really focused on technicalities, then I would suggest going for the Clear, as then you don't have to worry about EQ.

I'm not sure why you asked about whether "most people" could tell a difference. In audio, what "most people" think is irrelevant. Your ears are not anybody else's ears. Your preferences are not exactly the same as anybody else's preferences. Things that bother some people don't bother others. Will there be differences after EQing the Elex to sound like the Clear? Almost certainly, they won't sound exactly the same. Whether that matters is something that only you can answer for yourself.