Forward requests on Public IP of VM on Azure to Private IP of VM on primise

Good morning,

my goal is to redirect a request that comes from the public IP address in Azure vm1 to another vm2 that does not have a public IP address on premise,

Example :

Vm1: local ip: 10.10.18.2, public ip: 20.20.20.20

Vm2: local ip: 10.10.19.2 (on premise )

When VM1 receives a request through the public address 20.20.20.20, I would like it to be redirected directly to Vm2 which is on premise.

Knowing VM1 AND VM2 communicate through VPN software.

Is there a way to do this?

Thank you a