I tried using a profile per https://blog.simos.info/how-to-get-lxd-containers-get-ip-from-the-lan-with-routed-network/ and
$ lxc launch images:fedora/33/cloud myfedora --profile default --profile routed
Creating myfedora
Starting myfedora
$ lxc shell myfedora
[root@myfedora ~]# ifconfig
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1000 (Local Loopback)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@myfedora ~]# ifconfig eth0 up
[root@myfedora ~]# ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.1.201 netmask 255.255.255.255 broadcast 255.255.255.255
inet6 fe80::e495:5eff:fecc:8e2a prefixlen 64 scopeid 0x20<link>
ether e6:95:5e:a0:22:5e txqueuelen 1000 (Ethernet)
RX packets 11 bytes 1123 (1.0 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 19 bytes 1494 (1.4 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1000 (Local Loopback)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@fedora ~]# nmcli
eth0: connected (externally) to eth0
"eth0"
ethernet (veth), E6:95:5E:A0:22:5E, sw, mtu 1500
inet4 192.168.1.201/32
inet6 fe80::e495:5eff:fea0:832a/64
route6 ff00::/8
route6 fe80::/64
lo: unmanaged
"lo"
loopback (unknown), 00:00:00:00:00:00, sw, mtu 65536
Use "nmcli device show" to get complete information about known devices and
"nmcli connection show" to get an overview on active connection profiles.
Consult nmcli(1) and nmcli-examples(7) manual pages for complete usage details.
[root@myfedora ~]#
Requires more investigation. DNS requires to configure systemd-resolved (file /etc/systemd/resolved.conf).