@octylFractal thanks for the lead, are there any examples in the docs?

for kotlin-dsl, best do in root declare version, in subprojects dont declare versions

root/build.gradle.kts

plugins {
 kotlin("jvm") version "1.3.21"
}

root/subproject/build.gradle.kts

plugins {
 kotlin("jvm")
}

Alright thanks, this was very helpful. I did a minimal example here: https://github.com/thomasnield/kotlin_gradle_dsl_multiproject_examples