How to make an ability that increases certain ability scores temporarily

I want to use the ability section to automate a temporary increase to some ability scores by proficiency bonus given by a homebrew feat. Is there a way to do so? and to make it toggle-able?

Which character sheet are you using? 

Gauss said: Which character sheet are you using?  5e 2014 sheet

Yes, you can use equipment to increase ability scores. Checkmark the equipment on and it will apply the bonus to the ability scores. But you will have to put a numeric value, not directly reference the proficiency bonus. Ie: you will need to adjust the value whenever your proficiency bonus increases.  An example:  In the Mods line of the equipment put "Strength +3" (without quotes) and it will increase the strength value by 3.