How to play not xbox series games

Because on my Xbox series x, it only shows 'Optimized for series x/s' but if a xbox series x version of a game is NOT 'optimized' how would i know if I'm playing a series x/s version of a game?

You are misunderstanding how it works

You can pre-order games all you want doesn't mean you can download and play series s/x consoles games

Xbox one games are just xbox one games it doesn't matter which xbox one you have all xbox one games work with xbox one

This is why series consoles are labeled series not xbox one series s

I have several disc games for my Xbox One, i am buying a Series S, but how will i pay them on it?

You wouldnt. Xbox Series S can only play digital games so if you want to play them on Series S you would have to repurchase them digitally.

Hello GinTokiSAKATA how are you?
My name is Ezequiel. I'm an Independent Consultant. Unfortunately your purchase of the game is only licensed to play on XBox Series X and Series S.

Due to the complexities of the Series S and X and how they work, Series X/S games can only be played from either the internal drive or the official expansion card. Game drives can only play older games, from XBox One and back. You can store Series X/S games on the drive, just cannot run them from it