Fixed-width terminal independent of window size

[sassanh]

• nvim --version: master-4a996bc
• vim -u DEFAULTS (version: ) behaves differently? No
• Operating system/version: macOS Catalina
• Terminal name/version: iTerm2
• $TERM: xterm-256color

Steps to reproduce using nvim -u NORC

nvim -u NORC
:terminal
bash
while true; do echo '1234567890a1234567890b1234567890c1234567890d1234567890e1234567890f1234567890g1234567890h1234567890i1234567890j1234567890k1234567890l1234567890m1234567890n1234567890o1234567890p1234567890q1234567890r1234567890s1234567890t1234567890u1234567890v1234567890w1234567890x1234567890y1234567890z'; sleep 1; done
<c-\><c-n>:vs
:q

Actual behaviour

You see the width of the terminal changes

Expected behaviour

I would like to be able to set a fixed width/columns for the terminal so that it works regardless of the window it is displayed in