I think you’re confusing FLASH memory with SD. The SD card only holds the sound files and some .ini files, it does not hold your styles AND Arduino can’t see what’s in it. You probably mean you’ve exceeded FLASH memory, which is the memory available on your board. You cannot fit more on the board than the available memory so you will need to reduce the size of your config and/or take steps to save memory (although 30 styles is a good amount depending on complexity). Now if you want to have more presets you can create copies of the existing presets and then change fonts and settings if you have Edit Mode enabled styles and use Edit Mode or ProffieOS Workbench. You can create as many presets as you want by combining fonts and styles but you can only fit a fixed number of styles onto the board.
I recommend using my library to build Option Styles if you want to build many unique presets, depending on how you build the style you can create a single style that can then generate 100s of unique presets via Edit Mode of Workbench.
I discussed a bit here in the OS6 library: Let's Talk ProffieOS6 Style Library - Tonight 9:00pm EST - YouTube
And the new config tool also gives you ways to do with Using Functions and style arguments:
ProffieOS Config Helper Tool v3.0 Introduction (OS7 Feature Support and Config Optimization)
There are also other ways to save memory here:
ProffieOS Documentation: Saving FLASH Memory