I can't update my iOS device and this the screenshot of my software update there is no option

Based on your screenshot your iPhone Is up to date.

If it is an outdated iPhone it can’t be update to a higher iOS.

Tell us which iPhone you use.

I have an iphone 6s plus. The phone works perfectly fine and i do not want to buy a new phone. Several companies are telling me that the apps will no longer work unless i have a higher update. Why cant my phone have a newer update? It just seems very unfair to be forced to buy another new phone when mine works perfectly fine!

Are you sure that you have an iPhone 6s? What is the current iOS on the device? Go to Settings>General>About>Version. If you attempt to update, what do you see on the screen? My guess is you are seeing that the device is up to date with iOS 12.5.5, which is the highest iOS that an iPhone 6 can use and you have an iPhone 6. You will not be able to use a newer iOS on the iPhone 6, it does not have the hardware necessary to run the newer iOS.