Hello,

This function is already in the main plugin you can find the settings in below locations,

=> WooCommerce settings >> Points & Rewards >> Redeem Points >>
https://tinyurl.com/2s46y4mb

=> WooCommerce settings >> Points & Rewards >> Earned Points >>
https://tinyurl.com/3bk5p2ka

Do refer this screenshot to see how it works =>>
https://tinyurl.com/3w4f87uc

Note : This functionality will work only with taxation and will not work for shipping charges as due to restrictions from WooCommerce functionality.

Thanks.