Sign up for Apple One Premier using the same Apple ID that you used before.
Then see the following from What happens to your iCloud storage when you sign up for Apple One - Apple Support
If the iCloud storage included in Apple One is equal to your current plan
During the free trial, you keep both your current iCloud+ plan and the iCloud storage in Apple One. Once the trial is finished, your current iCloud+ plan is canceled. Your total iCloud storage will be the amount included in your Apple One subscription.
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After you subscribe to Apple One, you can buy more iCloud storage if you need more. With both Apple One and an iCloud+ plan, you can have up to 4TB of total iCloud storage.