Joomla Website Upgrade (5.4.7 → 6.1.2) + Compatibility & Testing

I need my Joomla site moved from version 5.4.7 to 6.1.2 while keeping everything running smoothly. The job includes: • Upgrading the Joomla core and database to 6.1.2 without data loss. • Updating our purchased themes so layouts, style settings, and overrides render perfectly on the new version... (Budget: $10 - $30 USD, Jobs: CSS, Database Management, HTML, Joomla, PHP, Web Design, Website Development, Website Testing)