Only 1 strap found in my new iwatch 8 45mm box

What extra strap?

The Apple Watch only comes with 1 strap in the box. There is no extra. If you bought an additional strap during your purchase of the Apple Watch, it would be in a box of its own.

You can verify that in the "What's in the box section" here ➜ Apple Watch Series 8 GPS, 45mm Starlight Aluminum Case - Apple

How many sections of band you get, will depend on the type of band you choose.

Some bands are only one elastic strip, other bands come in 2 sections, left and right, with a clasp to join them.

In the past some watches came with bands that offered a small side, and a larger version of the same side. Apple has not done this in a while.

click here ➜ Why is there two bands instead of three i… - Apple Community

The band wrist size its only one. The one you select during purchase.

You only get one band, of the size you selected.

Me too i find extra 1side not 2😢