Hi, in B2C you can use these Graph API's. You can try to use the profilePhoto resource type which lets you get/update a photo.
This may work:
GET https://graph.windows.net/myorganization/users/{user_id}/thumbnailPhoto?api-version
PATCH https://graph.windows.net/myorganization/users/{user_id}?api-version
If this answer helped you, please mark it as "Verified" so other users may reference it.
Thank you,
James