To reproduce run following code

public class Test extends Application {

    public static void main(String[] args) {
        launch();
    }

    private Parent getContent() {
        VBox list = new VBox(10);
         
        Button but = new Button("Button button buttton button button long long long long line");
        but.setWrapText(true);
// but.setStyle("-fx-wrap-text:true");
        but.setMaxWidth(50);
         
        list.getChildren().add(but);
        return list;
    }

    public void start(Stage stage) {
        stage.setX(100);
        stage.setY(100);
        stage.setWidth(200);
        stage.setHeight(200);
        Scene scene = new Scene(getContent());
        stage.setScene(scene);
        stage.show();
    }
}

import javafx.application.Application;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.Pane;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class ButtonWrap extends Application {

    public static void main(String[] args) {
        Application.launch(ButtonWrap.class, args);
    }

    private Parent getContent() {
        VBox list = new VBox(10);
        
        Button but = new Button("Button button buttton button button\n long long long long line");
        but.setWrapText(true);
        but.setMaxWidth(10);
        
        list.getChildren().add(but);
        return list;
    }

    public void start(Stage stage) {
        stage.setX(100);
        stage.setY(100);
        stage.setWidth(200);
        stage.setHeight(200);
        Scene scene = new Scene(getContent());
        stage.setScene(scene);
        stage.setVisible(true);
    }
}