Most LED fV depend on the color, and generally range from 1.8 to 3.4. If sticking with the same color family you are probably going to be ok like blue to green, but blue to red for example can require some extra resistors and such unless you really hunt hard for some red with a high fV which are out there but can be difficult to source. Using colored lens is one of easier ways to avoid the fV issue as they are usually in the same 3-3.4 range regardless of lens color.