Hello
You would have HA configured for LTM but only have the sync group for GTMs configured so that the GTMs respond independently of each other and the LTMs work as physical hardware backups for the other. It is not generally recommended that you combine GTM and LTMs on one platform but it can be done.
Use below for configuring GTM sync- https://my.f5.com/manage/s/article/K45907236
https://techdocs.f5.com/en-us/bigip-14-1-0/big-ip-device-service-clustering-administration-14-1-0/creating-an-active-standby-configuration-using-the-setup-utility.html
In GTM you. Need listener ips for accepting trafic. You can add all the GTM in sync, but not in HA
Br
Aswin