Unfortunately, there is no official version of Fouad WhatsApp for iOS devices. This is an Android app built for Android users to utilize the features of androids open source system allowing full customization. Of course the world is 85% Android users, and only iOS left among rest of other percent (almost be %15 market) can't use straight Fouad WhatsApp.
This is due to the restrictions in place with iOS. IOS is a closed platform from Apple, which focuses on full control of all third-party apps along with installation permissions — no downloadable app outside the App Store. However, the iOS app doesn't allow sideloading (that you can at least on some Android) because of its nature; while a lot of security restrictions for installing apps via APK existent in android OS be bypassed. It has been reported that few consumers — under 5% in the case of iPhone users — are willing to jailbreak their phones, due partly to security worries and the threat of voiding warranties.
On the other hand Fouad WhatsApp lives for altering Original interface & features of Whatsapp to be more advance like Custom Themes, Privacy Settings, Media sharing properties etc. Some of these features need system level permissions which are blocked by Apple to secure the user privacy and maintain security features of its System. So naturally a Fouad WhatsApp for iOS is just not compatible with Apple's tight straitjacket to personalize how things work sick of both lines getting used in one same comment on Android devices.
There are some reports where users install Fouad WhatsApp using third-party stores or unofficial sources. But, more often than not these are unreliable tactics that can (and I have seen ) get you into a lot of trouble! This is not the first time security analysts are warning against downloading apps from non-preferred venues, as these may render malware or a breach to your phone. As in 2020, iOS users were hit with phishing attempts by downloading modified apps from such sources.
Finally, the facts summarize that despite its relatively high popularity among modded WhatsApp users (being 3rd most preferred), there is no legit/safe version for iOS devices! If you are interested in WhatsApp alternatives that have been modded, what better place to be than Android? For those users who wants to explore Fouad WhatsApp they can check out the latest versions at official fouad whatsapp site.