ifconfig enp2s0:1 192.168.1.42
ip addr add dev enp2s0 192.168.42.1/24
ip addr add dev enp2s0 192.168.1.42/32 label enp2s0:1
Meanwhile having an explicit label can be nice in other situations if you want to replace an address instead of merely adding a new one.
I also seem to recall running into issues dealing with IPv6 with ifconfig that I worked around by switching to ip. I don't remember the specifics however.
Overall I wish ifconfig had been updated, I still find it a lot more user friendly that iproute. In particular the default output of a plain "ifconfig" is vastly more readable IMO: https://svkt.org/~simias/up/20200319-165513_ip.png
In general these days I use ip in scripts and ifconfig (when available) interactively. I don't love having to remember two ways of doing the same thing but I can't rely on ifconfig being available in scripts anymore and I just waste too much time parsing ip's bad output when I'm messing with networking interactively.
# ip a a 192.168.1.32/24 dev eth0
Then put 192.168.1.1 into browser etc. Do job. Back to term. Up arrow to get last command, change the second a to d (for delete) and the extra address is gone.
I use multiple addresses a lot, and recall having used them through ifconfig for years, probably well over a decade. Anyway, at least on Debian, the package net-tools brings ifconfig it back, again with full multiple addresses support.