I have made the subscription for 200GB deducted but my iCloud storage remains the same.

Manikjo wrote:

but my storage remains same.

If you do not see the upgrade you can always check how much iCloud storage you're using in Settings on your device, on a Mac, or on iCloud.com

- On your iPhone, iPad, or iPod touch, go to Settings > [your name] > iCloud.

- macOS Ventura: Choose Apple menu > System Settings, click [your name] at the top of the sidebar, then click iCloud on the right.

- macOS 12 or earlier: Choose Apple menu > System Preferences, click Apple ID, then click iCloud.

- On iCloud.com --> https://iCloud.com

ref: Check your iCloud storage on any device - Apple Support

Manage your iCloud storage - Apple Support

If it still won't show, report the issue to Apple --> Choose your country or region - Official Apple Support Select your country, then a product.

or:

Worldwide iTunes support - Choose your country or region - Official Apple Support

If you have upgraded iCloud storage, once your request for iCloud+ has been activated, you should receive an invoice in your email box.

Check -> Go to -> Settings -> your name -> iCloud -> if you see 50 GB (or 200 GB or 2 TB) then you have an iCloud subscription.

If you have an iCloud subscription, you will receive a monthly bill from Apple, check your email box.

You pay monthly for iCloud storage.

See -> How to use iCloud on iPhone -> How to use iCloud on iPhone – Apple Support (UK)