Will turning off location services lock correct location on my Mac mini?

OP wrote " I read that if I use my phone to create a local hotspot and log into it with my Mac Mini, it will get the true location."

When you turn on Location Services, you allow apps and websites to gather and use information based on the current location of your Mac. Your Mac determines its location using information from local Wi-Fi networks

An iPhone on the other hand, has GPS abilities that Apple Computers do not

Turning off location services altogether will essentially prevent your mac from knowing where it is. Why would you want that? You don't have to take such a drastic approach. Only grant access to location to the apps you want; there is no need to turn it off completely.

To answer your question directly: no, it won't "lock" your location.