I printed this multicolor, red base, white letters. Sliced with Cura using this method. https://www.youtube.com/watch?v=1nBnVtOEAiY
My first multicolor print, came out ok. Printed at 60 mm/s, with a pause after the third layer.
Settings on Ender 3
Speed - 60 mm/s
Layer Height - 0.2
Make sure all layers are fully printed or use 100% infill but I just set the bottom and top layers to 4 and it prints them fully!