Joomla 3 to 6 upgrade for a backend CRM

Need someone who is a PHP Joomla developer to upgrade a backend CRM application which is made on Joomla 1) Joomla need to update to latest version 6.1.2 (currently 3.3.6) 2) Website PHP version need to update to latest 8.5.8 (currently 5.6 ) We need a candidate who has setup an AI powered IDE so that AI can assist and test this - please apply explaining how you will do this / time taken / how will you do atleast a basic testing.