Global Modifier for Crit Range 5e OGL?

I have a Hexblade Warlock who once a day can perform Curse of the Hexblade improving his critical change from 20+ to 19+. Is there a way to set this up like a Global Modifier on the 5e OGL Sheet? Otherwise, and I've always wondered this, is there a way to just roll Critical Damage on weapon attacks with some sort of modifier key like Fantasy Grounds and Foundry do?

You can change the crit chance on an individual attack basis. There is currently no way to modify the critical hit value through a global modifier. You could re purpose the die roll field in the Character Settings, but this would also impact the checks and saving throw roll. Not that it really matters since only attacks can crit. Ability Checks and Savings Throws cannot crit per RAW.