You are already using the plugin block, so just add the gradle plugin in the outermost build.gradle....

# squarelibraries

[hfhbd]

You are already using the plugin block, so just add the gradle plugin in the outermost build.gradle.kts:

group "com.example"
version "1.0-SNAPSHOT"

allprojects {
    repositories {
        google()
        mavenCentral()
        maven("<https://maven.pkg.jetbrains.space/public/p/compose/dev>")
    }
}

plugins {
    kotlin("multiplatform") apply false
    kotlin("android") apply false
    id("com.android.application") apply false
    id("com.android.library") apply false
    id("org.jetbrains.compose") apply false
    id("com.squareup.sqldelight) version "1.5.3" apply false // or define the version in other places like the kotlin version
}

And apply the plugin in the sub project, eg app:

plugins {
    kotlin("multiplatform")
    kotlin("android")
    id("com.android.application")
    id("com.android.library")
    id("org.jetbrains.compose")
    id("com.squareup.sqldelight)
}