We are unable to setting the default values directly in Jenkins pipelines. However, we can attain a similar effect by using a combination of conditional logic and environment variables. Lets see how we can set a default value and return it in a Jenkins pipeline:

pipeline {
    agent any

    environment {
        Favcolor = 'Blue'

    stages {
        stage('Enter color') {
            steps {
                script {
                    def color = input(
                        id: 'color', 
                        message: 'Please select an option (Press "Proceed" to use default):', 
                        parameters: [
                            choice(choices: ['Blue', 'Green', 'Red'], description: 'Select an option', name: 'CHOICE')

                    // If the user didn't provide input, use the default choice
                    def selectedChoice = color ? color : env.Favcolor

                    echo "Selected choice: ${selectedChoice}"

                    // Use the selectedChoice variable in subsequent stages or steps
        // Other stages of the pipeline

In this example, we're using the env.Favcolor environment variable to set and store the default choice. When the input step is executed, if the user doesn't provide input, we fall back to the default choice stored in the environment variable. If the user provides input, we use their choice.

This method allows you to set a default choice and return it in the pipeline execution, and you can then use the selectedChoice variable in subsequent stages or steps as needed.