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Check your iCloud storage on any device – Apple Support (UK)

mostly such things are phishing Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

Identify legitimate emails from the App Store or iTunes Store – Apple Support (UK)

Open settings, tap on your name at the top, tap on iCloud. Your iCloud usage will be displayed at the top of the screen.

AcornAcres95 wrote:

I keep getting a text That says my iCloud is full. None of my other devices tell me that the iCloud is full is this a scam or is that true?

Yes it is a scam. Hopefully you didn't click on any links or enter any personal info in text message.