Hi I’m looking for a choir effect but all I found is “robotic” choir effects for guittars.
What I’m looking for is a way to make my singing voice sound like it’s a choir singing (like in churches).
Thanks!
It’s known as “Chorus” effect. Audacity does not have a built-in Chorus effect, but you can try
Blue Cat's Chorus - Smooth Chorus Effect (AU, VST, VST3, AAX Plug-in) (Freeware) which is a VST effect or Chorus Effect which is a Nyquist effect.
See Missing features - Audacity Support for how to install Nyquist plug-ins.
See Audacity Manual for how to install VST plug-ins.
It makes it much harder to help you if you don’t say what operating system you have or what version of Audacity you are using. You can’t use VST’s in Audacity on Linux.
Gale
Steve made a multi-voice chorus plugin for Audacity which is here … Chorus Effect
Yes - I’d already linked to it in my previous post. 
Is it better than Blue Cat? I noticed you have recommended Blue Cat in the past.
Gale
Oops 
If one has the choice go for Blue Cat Chorus , ( sorry Steve-D ).
Steve Harris offers a Multi-voice chorus … Steve Harris' LADSPA Plugin Docs
[ but I (on Windows) could only get the Steve-H chorus to produce useful results when only two voices were selected : it glitched when a higher value was selected ].
A chorus effect with a single voice isn’t going to sound like a real choir. With a real choir, you’ve got different voices with different timbre, often singing different parts and harmonies. And the parts & variations are written in the music, not randomly computer generated.
I’m not saying you can’t get a good effect, I’m just saying it’s not going to sound like a real choir.
You’ll get somewhat better results if you record yourself singing 2 or more times and mix those tracks together before applying a chorus effect. The natural differences in timing, phase, and pitch are difficult to fake.
And if you want it so sound like you are in a church, add some reverb.
You can also look for a harmonize effect, but again it’s not going to sound like two or more people harmonizing… If you are lucky, it will sound like you are harmonizing with yourself.
With any of these effects, you may get better results with a commercial plug-in than with a free one… In any case, effects from different developers/vendors will generally sound different.