How to activate vpn on my iphone7

Hi,

You need to either download your VPN provider app in the App Store or configure it manually in the settings (for a manual config, it needs to be either L2TP, IPSec or IKEv2) :

Hi

Various third-party VPN apps for iPhone are available from the App Store.

Supported protocols are detailed here:

About VPN protocols for iPhone, iPad, and iPod touch - Apple Support