Well, it seems something is wrong with your original math, but if all you want is a comparison to what other PC could do, and considering you can only do that combo once per fight and that you need a previous round to actually set it up, if you are using hex + hexblade curse, we have from the PHB only (ignoring complements and unearthed arcana articles):
A sorcerer 11 / warlock 2 with cha 20 could hex and on the next round agonizing eldritch blast + quicken lvl 6 scorching ray for 3d10 + 3x5 + 3d6 + 14d6 + 7d6 = 115.5, or 120.5 if draconic bloodline (fire). They also empower both spells, potentially increasing the damage at least of the scorching ray, considering the amount of dice being rolled. And they could do it all again on the next round, albeit at a lower power (lvl 5 scorching ray, for 105/110 dmg). A lvl 13 sorcerer with the magic initiate feat (taking hex + eldritch blast) would be able to something similar, with a higher level spell slot for the scorching ray but without the agonizing invocation. There are other combos that net more damage, some of them at more limited circumstances (something on the lines of hasted assassin rogue/warlock/sorcerer against surprised victim).
Even on a game without feats or multiclass, a fire dragon sorcerer 13 can quicken lvl 7 disintegrate + firebolt for 107 dmg, but only once per day, or twin lvl 7 disintegrate for 85.5 dmg against two targets, while a GWM PAM paladin 13 alone can smite for (5.5 + 10 + 4 + 4.5*4)*2 + bonus action (2.5 + 10 + 4 +4.5*5) for a total of 114 once per day, using 2 3rd level slots + 1 4th level slot for the smites, although as mentioned by Sorcerers Apprentice, it gets less likely to pull off the whole trick when you are using the -5/+10 part of GWM.
