What if I don't want ANSI/VT-100?

This is basically what modern terminal emulators still do -- but the Unix world was so consumed by DEC VT terminals back in the day that almost all any of them can emulate is VT terminals. (curses papers over most of the cross-terminal differences the emulators create so carefully, so it's almost academic what they're emulating anyway. These days with all the extra escapes what they're emulating is to some degree themselves!)

xterm itself can also emulate a Tektronix 4014, an early graphics terminal, but that was largely useful in the early days: other than gnuplot it's been decades since I saw anything that knew how to render any output on a Tektronix. If something wants to produce graphical output these days there are many better options. :)