Please refer to the steps below on how to enable XenApp/XenDesktop with NetScaler 12.0 with SSL A+ and HTTP2 support
login to NetScaler via CLI and look for VPN vServer configured
add vpn vserver **_XD_172.16.1.10_443** SSL 172.16.1.10 443
Replace the vServer with VPN vServer and harden it by following the link below
https://aventistech.com/2018/07/ssl-test-with-a-result-in-netscaler-vpx/
You should get the A+ Score for your XenApp / XenDesktop now
Enable HTTP2
Find the HTTP profile name that associate with the VPN vserver
show VPN vserver
1) _XD_172.16.1.10_443 (172.16.1.10:443) - SSL Type: CONTENT
State: UP
Down state flush: ENABLED
Loginonce: OFF
Disable Primary Vserver On Down : DISABLED
TCP profile name: nstcp_default_XA_XD_profile
HTTP profile name: nshttp_default_strict_validation
Appflow logging: ENABLED
Authentication : ON
DeploymentType : ICA_STOREFRONT
Device Certificate Check: OFF
CGInfra Homepage Redirect : ENABLED
Current AAA Sessions: 0
Total Connected Users: 0
Icaonlylicense : OFF IcaProxySessionMigration : OFF
DoubleHop : DISABLED Dtls : ON L2Conn: OFF
Max Login Attempts: 0 Failed Login Timeout 0
Fully qualified domain name: citrix.aventistech.info
Listen Policy: NONE
IcmpResponse: PASSIVE
RHIstate: PASSIVE
Traffic Domain: 0
Enable HTTP2, Direct HTTP/2 and Direct HTTP/2 using Alternative Service with the following command
set ns httpProfile nshttp_default_strict_validation -http2 ENABLED -http2Direct ENABLED -altsvc ENABLED
Verify the HTTP2 is enabled via https://tools.keycdn.com/http2-test
Reference
1. https://docs.citrix.com/en-us/netscaler/12/system/http-configurations/configuring-http2.html