Q.I Have A Lovely SAGO PALM But The Fronds Have Begun To Turn Brown And Crunchy.
I’ve been watering it regularly — if anything, perhaps too much. What to do? Shall I prune the fronds?”

Certified GKH Gardening Expert
If it's the older leaves turning brown, the plant may be purging its old leaves which is normal. If it's newer leaves turning brown, there is a problem. Sagos should be allowed to dry out between waterings. If you think you've overwatered, and the plant has root rot, it's important to repot right away in fresh soil and a clean container with drainage. It also could be a nutrient problem if you don't fertilize.
These articles should help:
https://www.gardeningknowhow.com/ornamental/trees/sago-palm/how-to-care-for-sago-palms.htm
https://www.gardeningknowhow.com/ornamental/trees/sago-palm/sago-palm-turning-brown.htm
https://www.gardeningknowhow.com/ornamental/trees/sago-palm/sago-palm-rot-diseases.htm
https://www.gardeningknowhow.com/ornamental/trees/sago-palm/sago-palm-watering.htm
https://www.gardeningknowhow.com/ornamental/trees/sago-palm/fertilizing-sago-palms.htm