How can I share subscription of magazine to another ipad

All of your purchased subscription services are available to all of your own devices that are signed-in to iCloud with the same AppleID.

Assuming that you wife has her own devices with her own AppleID, you may be able to share your App purchases and Apple subscription services using Family Sharing:

Family Sharing - Apple

Set up Family Sharing – Apple Support

Share App Store, iTunes Store and Apple Books purchases with Family Sharing – Apple Support

https://www.imore.com/how-set-up-family-sharing-iphone-ipad

As I mentioned, subscriptions purchased through Apple may be shared.

External service subscriptions, purchased outside of Apple’s own media services (such as Apple’s Books and Music Stores) are often tied to a specific individual.