Fully welded on is probably something done by a 3rd party shop. All 6th gen Celica come stock from the factory with bolt-on exhaust.
The exhaust system is a full cat-back exhaust. meaning that it includes the muffler-canister and the exhaust pipe + tip.
TRD exhaust with both pieces separated, but connecting with bolts.
The entire system bolts on to your header exhaust piping, and the rest uses rubber exhaust hangers.
https://celicahobby.com/forums/ubbthreads.php/topics/18819/exhaust-how-to-unbolt.html