We are aware that a lot of ESSEC incoming students have questions regarding their visa, their flight booking because of the situation caused by the Covid-19.
First, consult this link regularly
ESSEC update on Coronavirus COVID-19 / Actualités ESSEC sur le Coronavirus COVID-19 /
Second, if you have to apply for a French entry visa, you can proceed with Campus France. Keep in mind the recommendations made by consulates that apply even more under the Covid-19 cirmcumstances, that is wait until you have obtained your visa before you book your flight.
Or, make sure that your flight can be modified.