How to put `apply(plugin = "java")` and idea plugin into an external gradle.kts file

I want to put some common configurations (such as things of java,intellij,gradle,kotlin) into an external file and share it with other projects.

// myPropject/build.gradle.kts
buildscript {
    apply("/home/xiaojie/IdeaProjects/Config/gradle/kotlin/java-11/env.gradle.kts")
}

This is an external file:

///home/xiaojie/IdeaProjects/Config/gradle/kotlin/java-11/env.gradle.kts
repositories {
    mavenLocal()
    jcenter()
    mavenCentral()
    gradlePluginPortal()
    maven {
        url=uri("https://plugins.gradle.org/m2/")
    }
}

apply(plugin = "java")
java {
    toolchain {
        languageVersion.set(JavaLanguageVersion.of(11))
    }
}

Here are the error messages:

> Configure project :
e: /home/xiaojie/IdeaProjects/Config/gradle/kotlin/java-11/env.gradle.kts:15:1: Expression 'java' cannot be invoked as a function. The function 'invoke()' is not found
e: /home/xiaojie/IdeaProjects/Config/gradle/kotlin/java-11/env.gradle.kts:15:1: Unresolved reference. None of the following candidates is applicable because of receiver type mismatch: 
public val PluginDependenciesSpec.java: PluginDependencySpec defined in org.gradle.kotlin.dsl
e: /home/xiaojie/IdeaProjects/Config/gradle/kotlin/java-11/env.gradle.kts:16:5: Unresolved reference: toolchain
e: /home/xiaojie/IdeaProjects/Config/gradle/kotlin/java-11/env.gradle.kts:17:9: Unresolved reference: languageVersion

FAILURE: Build failed with an exception.

* Where:
Script '/home/xiaojie/IdeaProjects/Config/gradle/kotlin/java-11/env.gradle.kts' line: 15

* What went wrong:
Script compilation errors:

  Line 15: java {
           ^ Expression 'java' cannot be invoked as a function. The function 'invoke()' is not found

  Line 15: java {
           ^ Unresolved reference. None of the following candidates is applicable because of receiver type mismatch: 
               public val PluginDependenciesSpec.java: PluginDependencySpec defined in org.gradle.kotlin.dsl

  Line 16:     toolchain {
               ^ Unresolved reference: toolchain

  Line 17:         languageVersion.set(JavaLanguageVersion.of(11))
                   ^ Unresolved reference: languageVersion