The following documents will also help you for sure:
https://www.fir3net.com/Firewalls/Juniper/srx-dyn.html
https://kb.juniper.net/InfoCenter/index?page=content&id=KB28077&actp=search
https://www.oreilly.com/library/view/juniper-srx-series/9781449339029/ch10.html#configuring_dynamic_gateways_and_remote (check "Configuring an IKE gateway with a dynamic IP address" section)