Changing plan - What happens to shared links

Switching from a Microsoft 365 Family subscription to a Personal subscription should not affect your existing OneDrive shared links, so far i know.

The files and folders you've shared will continue to be accessible to those you've shared them with. The primary difference between these subscriptions is that the Family plan allows sharing the subscription benefits with up to five other users, each receiving 1 TB of OneDrive storage, whereas the Personal plan is intended for a single user with 1 TB of storage.

This change doesn't impact the accessibility of your shared files.

However, it's important to ensure that your total OneDrive storage usage doesn't exceed the 1 TB limit of the Personal plan. If your current usage surpasses this limit, you may need to reduce your stored data to fit within the new storage capacity.

For more detailed information on sharing files and managing permissions in OneDrive, you can refer to Microsoft's official support page:

Share OneDrive files and folders

My answers are voluntary and without guarantee!

Hope this will help you.