Be careful about any get rich quick schemes on stocks that you might read or hear about. The goal with investing your emergency fund is to not expose your cash to an insane amount of risk.
Before I had started to really invest my emergency fund, I was doing a lot of side jobs and freelance work too. This helped build a decent amount of savings and gave me a financial cushion in case of a job loss on the full-time gig.
Basically, this also goes with having a stable job or side hustle. But if you are not living paycheck to paycheck then it may be a good time to invest.