Yes It is possible, I thought you were using SSL VPN, If you're using dialup VPN the traffic flow will be same. In Dialup VPN configuration which you're using for remote VPN, add the traffic selector to access LAN1 and LAN2 subnet. In VPN configuration between Fortigate 1 and Fortigate 2 add a new traffic selector with Dialup VPN client IP range as local and LAN2 subnet as remote on Fortigate 1, and vice versa on Fortigate 2
Create Policy on Fortigate 1 from dialup VPN to Ipsec VPN with source dialup range with user and destination LAN2, on remote side create a policy from LAN2 towards Ipsec with source LAN2 and destination dialup VPN range, traffic will work as expected.
The Fortinet Security Fabric brings together the concepts of convergence and consolidation to provide comprehensive cybersecurity protection for all users, devices, and applications and across all network edges.