Of course in 1987 a Macintosh II with a fully expanded "Toby" framebuffer could not only do 256 colours, it could do it in 640x480 mode where as a PS/2's VGA could only do 16 colours at that resolution. And an Amiga could only do flickervision at that res.
Of course with technology improving all the time, not having a updated chipset circa 1987 that at least had a progressive scan 640x480(ish) is one of those things that really killed the chances of Amiga as a serious computer. They only got that circa 1990, and "Super VGA" was already just about becoming a thing in the PC world (and Microsoft had kinda got round to making a version of Windows that didn't suck by then). I'm not sure if the mythical Ranger had a progressive mode, but it's it does show how Commodore inability to keep the custom chips updated in a timely mannner slowly sunk the system...
If cost is no issue, the PS/2 also had the 8514/A card that could do 256 colours at 1024x768. And there was also the PGC from 1984 that could do 256 colours at 640x480.
I guess you weren't there.
Dynamic hires ran at 640x400x16 colors, but changed the palette on every single scanline, which could allow display of all 4096 colors in hires). Sliced HAM did the same thing, but in 320x400 HAM (the base palette was 16 colors and could be used directly without fringing, so changing those 16 colors every line would reduce fringing while still allowing more than 16 colors to appear on a scanline).
Nothing stopped people from using this dynamic palette technique with 32-color lores or 64-color EHB as well. But it was most commonly used in the two forms I mentioned.
By the time HAM8 came around in the AGA chipset, this wasn't really needed, as HAM8 fringing was much less noticeable, having a base palette of 64 colors. There's no reason you couldn't do sliced HAM8 however, although I'm not sure if you could change all 64 base colors for each scanline.
That's the highly special hold-and-modify mode (https://en.wikipedia.org/wiki/Hold-And-Modify). I tried pretty hard to word my comment fairly, remembering the sometimes legendary tenacity of Amiga fans. (Which nowadays includes yours truly.)
Technology advanced much more rapidly in those days. Similar to how hard drive capacity seemed to double every six months for a while, or how there's a new bleeding edge AI model every three months today.
Also, VGA had 256 colors. The Amiga had 4,096 simultaneously.