how to use WHEN query eloquent in laravel code example

Example 1: laravel update first

Model::where(['x' => 1, 'y' => 2])->first()->update([...]);

Example 2: laravel find query

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Flight extends Model
{
    /**
     * Indicates if the model should be timestamped.
     *
     * @var bool
     */
    public $timestamps = false;
}