Maybe. Many will not hide themselves very well, but some use their power to make themselves invisible (often called a "rootkit"). I think the most promising approach to avoiding them is to use "secure boot" where the hardware verifies a signature on the firmware, which in turn verifies a signature on the OS, etc. ChromeOS devices (and some smartphones?) are pretty good at this. However, secure boot also prevents you, the rightful owner, from hacking (customizing) your own machine, which kind of sucks.
