Beast Mode Change font size

I am using a dynamic textbox so that I can get a year on year comparison in my card which shows a percentage. However the font size of the year on year value is the same as the previous months value. I want to try to create a beast mode that will change the font size of this '%_change percent' so the value will look like  a second metric. I have been trying to filter it on max and min date, however I can't get this to work. I just want a year on year comparison but I want the value to be smaller than the previous months value and it to be also formatted in red and green depending on if it is above or below 0. Any help would be appreciated.