Neighbour/ARP tables management IP subcommand. More information: https://manned.org/ip-neighbour.8.
ip neighbour
eth0
:sudo ip neighbour flush dev eth0
ip neighbour get lookup_ip dev eth0
eth0
:sudo ip neighbour add|del ip_address lladdr mac_address dev eth0 nud reachable
eth0
:sudo ip neighbour change|replace ip_address lladdr new_mac_address dev eth0