If you have or can get enough contrast, such as darker joints, it is easy. Also, you can change bump 'amount' setting in material between 'plus' and 'minus' to extrude or inset. Or is it vice-versa ??
https://www.deviantart.com/nik-2213/art/Oops-840124790
https://www.deviantart.com/nik-2213...shoot-843690347
A 'gotcha' is that object Properties --side-kick to Parameters-- has an oft-overlooked 'Displacement Bounds' dial. Set too low, it inhibits significant 'relief' or 'intaglio' forming...
Getting vertical scaling 'right' for landscapes may need
many trial renders. Really, really helps to know the horizontal scaling. I even found and measured that volcano on Google Earth, was still 'off' by 20~~30 %. In the end, I shrugged and made a joke of it...
FWIW, that 'breached caldera' may feature in 'Erewhon'. This is my hypothetical, part-terraformed mega-moon of 'Freya', the real tau Ceti 'f', a super-Earth or sub-Neptunian, which is at cold edge of 'habitable' zone. I reckoned a face-locked mega-moon, tidally stirred, with 'Frey-Light' during almost all of each lonnng night, would be habitable. Well, sorta-kinda. Is actually in 'ice age', as a flush of vegetation ate most of the volcanic CO2 from last big eruption, killed its 'greenhouse effect'...
Imagine this caldera as part of a vast volcanic complex akin to Mars' Tharsis Rise, which straddles equator and faces Freya, Settlers dig in along the equator-facing slope of a vast out-flow canyon, just above spring-line. Too high, they're subject to Katabatic winds. Too low, they're at risk from limnic eruptions, also known as lake overturns, per Lake Nyos. And, yes, every few years, there's an expedition to the lake, to 'depth-charge' it, make it safe again...
Thank you very much Nik! I didn't realize making a bump map, from the material itself (but I should have 
). Now, I'd like to apply it to floors which should look paved. instead of flat & smooth. 
... CO2 escaping from water & suffocating life forms, woah 
, that's something else!