Help with rich text

Help and Feedback Scripting Support
#1

How can I make the first letter of the string fontsize increased? I’m making a dialogue GUI and I want the first letter of the animated text to be slightly bigger, but I have no idea how to approach this

local function gSC(str)
			return string.sub(str,string.len(str)) or false
		end

		for i=1,string.len(Prompt.Value) do
			PromptFrame.Text = string.sub(Prompt.Value, 1, i)
			if gSC(string.sub(Prompt.Value, 1, i)) == "." then
				wait(.28)
			end
			if gSC(string.sub(Prompt.Value, 1, i)) == "," then
				wait(.12)
			end
			wait(0.08)
		end

This is the snippet of script that animates the text. The first letter should always be the one thats slightly bigger, and it returns to normal size after the next one appears.