I bought 2 TB of storage which is more than enough. If I cancel the subscription will I lose the 2 TB that I’ve paid for?

iCloud storage is billed monthly. See the following from Downgrade or cancel your iCloud+ plan - Apple Support

What happens when you downgrade or cancel iCloud+

• If your iCloud storage exceeds your new storage plan capacity, iCloud won't sync or update your information. iCloud updates again when you increase your storage capacity or delete information to make more space. 
• If you downgrade to the free iCloud plan, you will no longer have access to iCloud+ features like Hide My Email, Private Relay, and HomeKit Secure Video support.2
• If you pay for both Apple One and an iCloud+ plan, you can downgrade or cancel the iCloud+ plan and just use the iCloud+ plan included in Apple One.

No. You didn't actually buy it; you've been renting access to 2TB of space on Apple's servers.

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No, you're only renting storage. If you downgrade to the free plan, you will only have 5GB. Anything stored in excess of 5GB will be deleted.