There are two scenarios: Applying to VM the first time, on subsequent boots.

On first boot without the updated netplan config, when you first add it

root@ubuntu:/home/ubuntu# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth2-2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether b8:38:61:bc:60:f6 brd ff:ff:ff:ff:ff:ff
3: ens5: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 52:54:00:ef:88:a2 brd ff:ff:ff:ff:ff:ff
    inet 10.0.2.15/24 brd 10.0.2.255 scope global dynamic ens5
       valid_lft 86177sec preferred_lft 86177sec
    inet6 fe80::5054:ff:feef:88a2/64 scope link
       valid_lft forever preferred_lft forever


After a reboot initially the addresses are assigned.
root@ubuntu:/home/ubuntu# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth2-2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether b8:38:61:bc:60:f6 brd ff:ff:ff:ff:ff:ff
    inet 6.1.6.1/24 brd 6.1.6.255 scope global eth2-2
       valid_lft forever preferred_lft forever
    inet6 2006:1:6::1/116 scope global dadfailed tentative
       valid_lft forever preferred_lft forever
    inet6 fe80::ba38:61ff:febc:60f6/64 scope link
       valid_lft forever preferred_lft forever
3: ens5: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 52:54:00:ef:88:a2 brd ff:ff:ff:ff:ff:ff
    inet 10.0.2.15/24 brd 10.0.2.255 scope global dynamic ens5
       valid_lft 85262sec preferred_lft 85262sec
    inet6 fe80::5054:ff:feef:88a2/64 scope link
       valid_lft forever preferred_lft forever

However, if the addresses are cleared from the interface, networkd cannot
reapply the config and leaves the interface unconfigured

root@ubuntu:/home/ubuntu# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth2-2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether b8:38:61:bc:60:f6 brd ff:ff:ff:ff:ff:ff
3: ens5: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 52:54:00:ef:88:a2 brd ff:ff:ff:ff:ff:ff
    inet 10.0.2.15/24 brd 10.0.2.255 scope global dynamic ens5
       valid_lft 86177sec preferred_lft 86177sec
    inet6 fe80::5054:ff:feef:88a2/64 scope link
       valid_lft forever preferred_lft forever