=====================XAML Layout code=========================================
    <ContentPage.Content>
        <StackLayout>
            <Button 
                    x:Name="FirstButton"
                    Text="{Binding MText1}" 
                    Style="{StaticResource MButton}" 
                    BackgroundColor="{Binding MButtBckColor1}" 
                    Command="{Binding ChangeColorMCommand}"
                    CommandParameter="{x:Reference FirstButton}"
                    ClassId="{Binding MId1}"
                    ></Button>
            <Button Text="Next" Grid.Row="1" Grid.Column="1"  BackgroundColor="Green" TextColor="Black" TextTransform="None" Command="{Binding RestCommand}"></Button>
        </StackLayout>

    </ContentPage.Content>


=====================Background code========================================
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;

namespace App2.Views
{
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class Page1 : ContentPage
    {
        public Page1()
        {
            InitializeComponent();

            BindingContext = new MyViewModel();
        }
    }

    internal class MyViewModel: INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;
        Xamarin.Forms.Color mButtBckColor1 = Xamarin.Forms.Color.White;
        public Xamarin.Forms.Color MButtBckColor1
        {
            get { return mButtBckColor1; }
            set
            {
                mButtBckColor1 = value;
                OnPropertyChanged(nameof(MButtBckColor1));
            }
        }
        int mId1=1001;
        public int MId1
        {
            set
            {
                mId1 = value;
                OnPropertyChanged(nameof(MId1));
            }
            get { return mId1; }
        }      
        string mText1;
        private int idValue;

        public string MText1
        {
            set {
                mText1=value;
                OnPropertyChanged(nameof(MText1) ); 
            }
            get { return mText1; }
        }
        public ICommand RestCommand { private set; get; }
        public ICommand ChangeColorMCommand { private set; get; }
        public MyViewModel()
        {

            MText1 = "Color Test";
            MButtBckColor1 = Xamarin.Forms.Color.DarkCyan;

            RestCommand = new Command(() => ResetCellsData());

            ChangeColorMCommand = new Command((o) => ChangeClickEvne(o));
        }

        private void ChangeClickEvne(object sender)
        {
            var firstBUtton = sender as Button;
            var id=firstBUtton.ClassId;
            MButtBckColor1 = Xamarin.Forms.Color.Red;
        }
        private void ResetCellsData()
        {
            MButtBckColor1 = Xamarin.Forms.Color.DarkCyan;
            MText1 = "123";
        }

        protected virtual void OnPropertyChanged(string propertyName)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}


==================================Here is style in App.xaml==================================================

 <Application.Resources>
        <ResourceDictionary>

            <Style x:Key="MButton" TargetType="Button">
                <!--<Setter Property="CharacterSpacing" Value="4" />-->
                <Setter Property="TextColor" Value="AntiqueWhite" />
                <Setter Property="BorderRadius" Value="3" />
                <Setter Property="FontSize" Value="8" />
                <Setter Property="FontAttributes" Value="Bold"/>
                <Setter Property="TextTransform" Value="None"/>
                <Setter Property="BackgroundColor" Value="DarkCyan"/>
            </Style>
            
        </ResourceDictionary>        
    </Application.Resources>