Useful resources for this

https://dextrel.net/dextrel-start-page/design-ideas-2/mains-zero-crossing-detector

https://www.eevblog.com/forum/projects/mains-zero-crossing-detection

Zero crossing detect ICs

https://www.rohm.com/products/power-management/ac-voltage-zero-cross-detection-ics/bm1z001fj-product