Yeah, I wasn't saying anything because I couldn't remember. I think Debian puts it there. Try the interfaces man page.
There's also a route command. Maybe iproute too. Something like
route add 192.168.43.1 gw
(or gateway or default instead of gw).
On a command line. There's a routing table, and a way to show what's in it and clear it. See the route man page.
DHCP takes care of that so I forgot. I used to have to change my laptop over everytime I took it somewhere with DHCP and change it back when I got home. But that was OpenBSD too. And 10 years ago.
Just interfaces should work, that's what I use. It checks both.
Sent from my Motorola XT1527i