ah, I've got you covered. there are a few settings to help increase the chances of tall mountains.
1. lower the number of Erosion Cycles from the default value to like, half, or a quarter. Low settings allow cliffs to remain as cliffs.
2. change the 'elevation x - y' variance to a higher value than default. this will allow greater, well, variance between nearby map tiles
3. turn off Periodically Erode Extreme Cliffs.. not a big effect but it makes for nice looking cliffs
4. increase 'maximum number of subregions' count to maximum value. this will allow for smaller and more numerous subregions... to be honest I don't think this affects physical terrain generation. but it will allow a greater chance of unique mountain biomes so that's cool I guess?
these are not the end-all be-all, things like drainage and whatnot can also affect the terrain. but these settings will often result in very dramatic changes between biomes. I have found recently multiple 80+ z-level cliffs recently.
if you look for lakes next to mountains you are almost guaranteed a really nice cliffside over the water!!
all this being said, due to the way rivers erode the nearby terrain, you will likely never find a true river canyon, even with zero erosion cycles. the river placement flattens nearby terrain regardless of geological composition, so we will never find a long river akin to the grand canyon, except for very short sections near confluences or waterfalls.. sometimes you find some dramatic terrain that results from bugged generation as well, which makes for really interesting embarks.