Android studio create buildSrc but in build.gradle.kts implementation no found

Question

gradle version

distributionBase=GRADLE_USER_HOME
distributionUrl=https\://services.gradle.org/distributions/gradle-7.2-all.zip
distributionPath=wrapper/dists
zipStorePath=wrapper/dists
zipStoreBase=GRADLE_USER_HOME

buildSrc/src/build.gradle.kts

plugins{
    `kotlin-dsl`
}

repositories {
    google()
    mavenCentral()
    jcenter() // Warning: this repository is going to shut down soon
}
dependencies {
    implementation(rootProject.extra["androidPlugin"].toString())
    implementation(rootProject.extra["kotlinPlugin"].toString())
}

but implementation no found

i clone github coil project it can run and can found implementation

i want help