You should each keep your own accounts, then one of you get a 200GB plan and make sure it is shared with the other spouse as part of you both being in a Family sharing group.
"With Family Sharing, you can share a subscription to iCloud+ with everyone in your family group. This includes 50GB, 200GB, or 2TB of iCloud storage as well as features like iCloud Private Relay, Hide My Email, and HomeKit Secure Video support" Read this article to learn how to share iCloud+ with your family --> Share iCloud+ with your family - Apple Support
"When you share iCloud+, any family members using the free 5GB plan are added to your family plan automatically."
"If a family member is already paying for their own iCloud+ plan, they can choose to switch to your plan or keep their own and still remain part of the family. When they switch to the shared family plan, they get a refund for the remainder of their personal plan. They can't keep their current plan and use the shared family plan at the same time."
Switch from your personal iCloud+ plan to your family plan
Share iCloud+ with your family - Apple Support
"When you share an iCloud+ subscription, everyone in the family group uses their own account. That way your photos, documents, and other information stay private, even though you're sharing access to the service. You simply share the features and space available in iCloud+ with your family members, so you only have one plan to manage."