You can buy a cheap guitar echo/reverb pedal off of Amazon. I tried this one and it worked well.

https://smile.amazon.com/gp/product/B07413VS1F/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

You don't need to connect it inline with the mic. Plug a cable from FX Send of your mixer to the input of the pedal. Plug another cable from the output of the pedal to the Stereo Aux Return.

Use the FX knob on each channel to add the amount of echo/reverb effect desired.