Emulate a number of columns for a program in the terminal

I have a program that I'd like to run, deluding it to believe that my terminal has less columns than it does, because that enables its native truncation, which I need. I tried resize from xterm as suggested [on askubuntu](https://askubuntu.com/questions/852105/is-there-a-terminal-command-that-changes-the-terminal-window-dimensions) , however, that only works properly within xterm and can hardly be scripted. I need something that I can use within a script to get the output of a [taskwarrior](https://taskwarrior.org/) command. Exporting a different value for COLUMNS doesn't seem to change anything unfortunately.