How to check for spy software on your iPhone?

I would like to scan my iPhone for spy software. There is spy software like this one for instance:

https://autoforward.co/iphone-monitoring/

How could anyone find out if such software is installed on your iphone? Does Apple offer such a scanning service at the Genius bar? This question is not only meant for iPhones, all cell phones are meant in general, but I just happen to have an iPhone.

And another question: is it possible that someone at the network carrier can spy on you?

People have showed me videos of things just or only viewed through my phone's lens, they knew my password, and they knew things about stuff that only went through my phone.

Any kind of useful information is very much appreciated!

Best,

Xbal