Well, the easiest way would be to increase it’s length using Set Actor Transform/Add Actor Local Transform, but it will scale from the middle rather than adding more on one end.
I was trying to see if I could get it to work by attaching an instance of it to itself, using sockets, but I couldn’t figure it out.
If you manage to make a function that causes it to grow, or add a new segment on the end, you can just call it whenever he eats an apple. Have a hit box on the apple and in the apple blueprint call the function when it overlaps, then destroy the apple.