Here's an example configuration for your /etc/network/interfaces
using a simple ovsbr0 bridge for eth0, with dhcp for ipv4 and ipv6.
This was taken from https://bugs.debian.org/860786.

auto  ovsbr0
iface ovsbr0 inet dhcp
	ovs_type OVSBridge
        ovs_ports eth0

auto ovsbr0
iface ovsbr0 inet6 dhcp
        ovs_type OVSBridge
        ovs_ports eth0

autobr0 eth0
iface eth0 inet manual
        ovs_bridge ovsbr0
        ovs_type OVSPort

However, this didn't work for me. Instead, this worked:

auto br0
iface br0 inet dhcp
	ovs_type OVSBridge
	ovs_port enp0s3

auto enp0s3
iface enp0s3 inet manual
	ovs_bridge br0
	ovs_type OVSPort
	up ip address add 0/0 dev enp0s3
	up ip link set enp0s3 up
	up dhclient br0
	down ip link set enp0s3 down

 -- Antoine Beaupré <anarcat@debian.org>, Wed, 22 Jun 2022 12:02:39 -0400