Just a short Post Scriptum from my side:
I find the EVI formulas presented on the IDB website inconsistent.
First of all, for S2 bands 9, 5 and 1 are suggested for NIR, red and blue bands, respectively. This is at least bizarre selection, especially when Bands 1 and 9 are not a standard sen2cor output and are located outside atmospheric windows. Not to mention that band 5 is not red but red edge band.
A quick comparison with Landsat-specific EVI formulation shows differences in bands selection, which translates on value differences. So i would take the proposed formula with a pinch of salt.
After some consideration I think that the ‘optimal’ EVI formula for S2 is:
EVI = G*(B8A-B04)/(B8A + C1B04 - C2B02 +1)
where: G = 2.5, C1 = 6, C2 = 7.5 and L = 1.
B8A is selected here over B08 due to its better fit to the MODIS band range (using which EVI was developed and tested).