I seriously don’t get what you are trying to accomplish with this awful combo and why it would require you to rebalance the encounter.

For reference:

Hypnotic Gaze
Starting at 2nd level when you choose this school, your soft words and enchanting gaze can magically enthrall another creature. As an action, choose one creature that you can see within 5 feet of you. If the target can see or hear you, it must succeed on a Wisdom saving throw against your wizard spell save DC or be charmed by you until the end of your next turn. The charmed creature’s speed drops to 0, and the creature is incapacitated and visibly dazed.
On subsequent turns, you can use your action to maintain this effect, extending its duration until the end of your next turn. However, the effect ends if you move more than 5 feet away from the creature, if the creature can neither see nor hear you, or if the creature takes damage.
Once the effect ends, or if the creature succeeds on its initial saving throw against this effect, you can’t use this feature on that creature again until you finish a long rest.

Create Thrall
At 14th level, you gain the ability to infect a humanoid’s mind with the alien magic of your patron. You can use your action to touch an incapacitated humanoid. That creature is then charmed by you until a Remove Curse spell is cast on it, the charmed condition is removed from it, or you use this feature again.
You can communicate telepathically with the charmed creature as long as the two of you are on the same plane of existence.

A couple things stand out to me:

• you are postponing your 8th and 9th level arcanum for a very shitty two-turns combo in a game where the vast majority of fights end by turn 3.

• Hypnotic Gaze requires your wizard DC, but you dumped your INT because you are a Warlock. If you didn’t, your stats probably suck.

• Seriously, if you really, really want to thrall someone, just ask your resident fighter to deal a non-lethal blow when they defeat the enemy on turn 3 and use the thrall feature that way instead of… Whatever this thing is.

• this combo is not broken and doesn’t require you to rebalance your game in any way, shape or form. I’m in the camp of “I hate spellcasters because they break the game” and even I would not have a problem allowing this in my table. Your GOOchantment abomination could just take another level in warlock, learn Glibness and pass whatever mission-critical CHA check that way, or Dominate Monster if you want an actually useful charm effect mid-combat, or, I don’t know, Feeblemind? Sure, this combo is technically reusable, but realistically, what monster are you fighting that’s consistently failing a DC 14 WIS check at level 16? Like, is you really, really don’t want your party to pull this off for whatever reason, just use a legendary resistance (or fudge the dice).

• You mentioned using this combo for a villain? Warlocks also get Power Word Stun, and I doubt most of the party members have more than 150 HP at level 16. Again, combats in this game last 2-3 turns on average. Having your party member stunned for 1-2 turns immediately is better than having them charmed on turn 3. Or cast Maddening Darkness and turn everyone blind. Or pick literally any other spell in your arsenal. You are a level 16 warlock. This thing is barely passable for a level 3 midboss.