Yes, iPad theme for iPhone is available for free on cydia repository, you can install is unless you full fill the following requirements.

Requirements To Install iPad Theme

In order to install iPad theme you need to have a jailbroken iphone, you need to have winterboard installed from cydia repository, ZodTTD repository [ http://www.zodttd.com/repo/cydia/ ] must be added via cydia.

Once the above requirements are complete you can follow the procedure below to install the ipad theme on iphone.

1. Open cydia and search ipad or ipad complete you will find some ipad themes which you just need to install.

Some other ipad themes which you can install from cydia

2. After installing these theme you can activate the ipad theme through winterboard as shown in the image below.

That’s it done