Can I connect external speakers to Mac mini m1

You also need an amplifier or use powered speakers since the Mini audio

output power is only sufficient to drive headphones.

Yes, there is a 3.5mm aux port below the 2 USB-A or if it runs USB-A/USB-C plug it into the corresponding port

Yes, I assume you mean some professional or prosumer speakers (if not please specify) that use ¼" TS audio jacks. You need a 3.5mm stereo to single or dual ¼" speaker cable to do so. Like this: https://www.amazon.com/gp/product/B00ZKM3SDO/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1