How can I install the Aramean-Suryoyo language on my Apple ios 18.3?

Aramean-Suryoyo wrote:

How can I add the Serto (West Syriac) to the my iPhone list?

The only way to add keyboards to an iphone is to download them from the app store, so that is where you need to search for them.

Are you possibly really talking about fonts instead of keyboards, so you just need to add a Serto font to your iphone? See for example this page from Keyman:

https://help.keyman.com/keyboard/syriac_phonetic/1.3.1/syriac_phonetic

Fonts you add to an iOS device can unfortunately only be used in apps which have font menu, like Pages, and may not work everywhere. I use the app AnyFont to add fonts to my own devices.

Below is an example of the iPad Pages app using the Serto Jerusalem font with the Keyman keyboard. Unfortunately I have not found a way to change the keyboard keys themselves, which use Estrangelo East. Perhaps the Keyman folks would know if that can be done and how.

Refer to this. At the bottom of the spec all the languages that are supported are listed. --> iPhone 13 mini - Technical Specifications

Check this out:

https://keyman.com/keyboards/aramaic_hebrew

https://keyman.com/keyboards/syriac_aramaic