I've been using one Apple ID between my iPhone and my wife's iPhone and need to separate the two and create her own Apple ID but use the same iCloud account. How do I accomplish this?

One of you'll keep the current one as your own. Other person signs out of the Apple ID on all their devices and chooses the option to keep content on the device, if asked, then they will create their own Apple ID and sign into it and turn on their preferred iCloud options again.

Lastly, the original Apple ID will send a Family Share invite to the new ID. Set up Family Sharing - Apple Support

It's still not recommended to share an iCloud ID either, but if you wish to then you would just sign out of iTunes and App Store and not choose to sign out of iCloud.

Hi,

You will need to create your or your wife’s own account and log out of the current one on the device, do you know how to do this.

You can link yours and your wife’s together by using the family link feature on ICloud in settings.

Hope this helped anymore help needed just ask me.