If that functionality is already there and I missed it then I'm sorry, but what I want to do is be able to raise the max essence on a player. I got a suggestion here for my Genetics Reborn mod that would raise the max essence a player can have based on a gene.
As I said if there is already that functionality would you point me to where I can find it since I must have missed it.

The suggestion was more for a gene that lowers/removes the red zone (dipping into which requires the use of the anti-rejection drug in the mod.)

This would be similar to an augment in WIRED: More Augs. It lowers the bar for when you dip into the red zone by 20 (default start of red zone is 20 tolerance remaining).

Good idea. Will implement - potentially as a player attribute.

I assumed max essence was what effected the red zone, as in more essence means more things before you hit the red zone
Never played mod just skimmed through api code

Still a way to get more maximum essence without changing the configs is a good idea imo, as more and more augments come out down the line. (Not to mention ones added by other mods.)

The use of these two mods together would covers a broad spectrum of h+ possibilities.

Implemented in 0.2.10. If there's additional functionality you need please ask.