Show / lock DLC levels on the main menu

I’m planning a project that requires a menu that presents or locks DLC levels based upon whether the player owns the DLC or not. So if the player does not own the DLC, they won’t be able to click on the text/button on the menu that leads them to that level.

I know you can patch the base game to include all the base game and DLC levels in the menu and then use steam to check for which content the player owns. But how do you change the functionality of options within the main menu based on DLC ownership?

My plan thus far is to patch the game upon DLC releases so that the main menu lists the DLC levels but if they don’t own the DLC, they can’t click on it as it would be greyed out or something to that effect.

I honestly have no idea where to start, so any advice would be greatly appreciated.

p.s - my apologies if this is in the wrong subforum.