You cannot permanently change your PC hardware specs with software
You can change what your system reports by using virtual machines or emulators
You can change CPU performance behavior with power settings
You can change GPU performance behavior with driver settings
You can change RAM usage behavior with virtual memory settings
You can change storage performance behavior with disk optimization settings
You can change display resolution and refresh rate in system settings
You can change audio device behavior in sound settings
You can change network adapter behavior in adapter settings
You can change system information shown in some apps with registry edits or spoofing tools
You can change benchmark results by overclocking or underclocking
You can change available resources by closing background apps and services
You can change perceived performance by disabling visual effects
You can change game hardware detection by editing config files or launch options
You can change BIOS-related options only if your motherboard supports software control through vendor tools