is it safe to use 61W MacBook Pro charger to charge iPad 9th generation ?

Yes, you can use your Mac 61W USB-C Power Adapter with your iPad without adverse affects.

Assuming your iPad Pro was supplied with an Apple 20W USB-C Power Adapter (now standard for many models of iPad), your iPad will be able to optimally charge at its maximum supported charging rate ~20W. Using a higher wattage Power Adapter will offer no additional benefit for iPad charging, but does provide additional power capacity for other connected USB accessories which draw power from the USB bus.

Charge the iPad battery - Apple Support

yes, I'm using it for iPad Pro... even its 61w...it will charge ur iPad upto what the iPad can receive.. no worries