I think you are asking if PA NAT supports proxy arp. If so, the answer is yes and it is automatic.
See page 5 in the Understanding Palo Alto NAT documentation.
https://live.paloaltonetworks.com/t5/Documentation-Articles/Understanding-PAN-OS-NAT/ta-p/60965
Proxy-ARP for NAT Pools
The address pools are not bound to any interfaces. If the address pool is in the same subnet as the egress/ingress interface IP address, the firewall will respond to ARP requests received on that interface for the IP addresses configured in the pool. If the address pool is not in the same subnet as the egress interface IP address, you must configure the necessary routes on the upstream devices in order to ensure the response traffic after address translation is routed back to the firewall.
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