How to change a free plan to a family free plan

Cancel a subscription by following the link here:

If you want to cancel a subscription from Apple - Apple Support

When you cancel a subscription, it just prevents it from being renewed and you still have access to the service that you have already agreed to by double clicking the side button with the amount and terms on the screen, followed by authorization with Face ID. To request a refund on a purchase, you can use the link below. In most cases all transactions in the App Store are final due to the explicit actions needed for the purchase, but at times Apple may provide a compassionate refund.

Request a refund for apps or content that you bought from Apple - Apple Support

If your refund is approved, the funds are applied to the same payment method that you used to buy the item. Here's how long it takes for a refund to appear on your account or statement:

• Store credit—It might take up to 48 hours to see the refund in your Apple Account balance.
• Mobile phone billing—It might take up to 60 days for the statement to show the refund. Processing time might be affected by your carrier. You can contact your carrier for an update.
• Credit and debit cards, Apple Pay, Apple Cash, and all other payment methods—It might take up to 30 days for the statement to show the refund. If you don't see the refund after 30 days, contact your financial institution.

Check the status of a refund for apps or content that you bought from Apple - Apple Support

• What free plan are you referring to?
• Do you already have Family Sharing set up?