Steven Vachon

Simply display a different theme to your <a href="http://www.apple.com/ios/" rel="nofollow ugc">Apple iOS</a> (iPod/iPhone/iPad) users.
Another plugin to check out is <a href="https://wordpress.org/extend/plugins/wptouch/" rel="ugc">WPtouch</a>; but depending on your needs, it may be overpowered.
This plugin becomes especially useful with WordPress-powered full-Flash websites. Since Apple has chosen to block Adobe Flash technology, your markets may require an HTML fallback.

iOS Alternate Theme

Automatically switch to an alternate theme for Apple iOS devices (iPod, iPhone, iPad).

KDT-Solutions

Use the Adobe Embed API with Elementor or with a Shortcode.
This plugin uses the hosted Aobe Embed API and you need to sign up for a free account on https://documentcloud.adobe.com/dc-integration-creation-app-cdn/main.html?api=pdf-embed-api and register the domain you use to get an API key. Calls are made to https://documentcloud.adobe.com/view-sdk/viewer.js so please be aware of any data protection regulations. More info about the API can be found here: https://developer.adobe.com/document-services/docs/overview/pdf-embed-api/

PDF Widget

Use the Adobe Embed API with Elementor or with a Shortcode.

iOS Alternate Theme vs PDF Widget