How to configure perapp for VPN ?

per-app vpn is deployed with MDM solution. You must find per-app vpn config example in your MDM provider manual. For example: Citrix XenMobile manual for per-app vpn

Hello, as stated per-app is deployed with an MDM. The Apps, xml config file, and certificate must be distributed from the MDM. Here is some more information on that:

https://techdocs.f5.com/kb/en-us/products/big-ip_apm/manuals/related/f5-access-ios-migration-2-1-to-3-0.html

https://techdocs.f5.com/content/kb/en-us/products/big-ip_apm/manuals/related/apm-f5access-ios-3-0-0/_jcr_content/pdfAttach/download/file.res/apm_f5_access_ios_3-0-0.pdf

It sounds like what you are describing is more On Demand VPN:

https://devcentral.f5.com/s/articles/apm-cookbook-on-demand-vpn-for-ios-devices