No need to spend money for something like digitech "the drop" or whammy!
You can easily drop the tuning to f.ex to Eb with the Helix "simple pitch" (or pitch whamm). Just set it to -1 (for Eb), -2 (for D etc.) and Mix to 100 % and you are done. Works great, also with chords.
BUT CONSIDER:
you have to use a certain volume level at the amp - no need to go to 11 :-) - but you have to setup the amp volume high enough that the downtuned amp signal does no more "double" with the natural volume level of the strings. When i set up my - ralative low - practice volume level, it will not work for me.
Best way to check whats going on is setting the looper in front of the simple pitch (distorted amp after the pitch) and play a little riff. Then you can even set up diffrent pitches like Eb, D, C# in one Preset using severals pitch shifters asigned to diffrent footswitches, and switch easily through and see/hear what is going on.
btwy: you have to use a certain volume level at the amp - also when using digitech the drop or a variax, same thing, the volume level of the amplified signal must be loud enough so that you are no longer "confused?" from the original tune of the strings.