terrain anchors and iron are the keys.
Here, I made V shaped large rock walls with a raised terrain spike in the middle. That puts the 'ground' dark blue rocks at the first balcony level, but the inside of those is hollow and livable space. That gives 10 units (5 stone columns) tall for 'free'. Out of the ground I have iron supports all the way up to the topmost rocks.

https://steamcommunity.com/sharedfiles/filedetails/?id=2799499765

to go higher than this, you have to use a tree, natural cliffside (like build up a mountain), or those giant tall rocks etc. I didn't use any of those this time. My topmost layer required going a bit nuts with support; you can see one column is missing in the screenshot (I got it fixed, using 4 iron gates up that wall gave just enough extra to hold it).

'twisting' seems to help. That is, don't stack one on top of another, but shift so that the one above is sitting on two below. I didn't realize that was helping (or seeming to) until later, so mine are stacked. That might get one more level, not 100% sure. Even if it does not get you a level, it lets you knock a wall down without anything above falling apart, if you need to adjust something.

be prepared: This is a relatively thin tower (the rooms are diameter 5 floor tiles or just under) and I used a good 500 iron (many of my floors are rock though, and those need supports, if you use wood floors you may cut the number some).