How do I choose a real gray with no blue undertones?

Hi Sherry, I've struggled too but this video helped me a lot - https://www.youtube.com/watch?v=re69jT9EW88

What type of lighting do you have in the room?

The type and intensity of lighting can greatly effect the perceived color of the paint on the walls.

Incandescent generally emits a yellow tone, fluorescent a green or yellow, and LED a blue if cool, and a yellow if warm.

https://www.blueistyleblog.com/2019/06/choosing-paint-colors-pick-the-right-gray.html

You also need to consider the undertone of the paint you're choosing. Paint will either have cool (blue, green), warm (red, yellow) or neutral undertones. An associate at your paint store will be able to help you with this.

Here's another article to read! Maybe this can help!

https://www.blueistyleblog.com/2019/06/choosing-paint-colors-pick-the-right-gray.html?utm_medium=social&utm_source=pinterest&utm_campaign=tailwind_tribes&utm_content=tribes&utm_term=752116666_30426042_105309

Yes, whether the undertone of a paint color is cool or warm will also affect the outcome. The link posted in my comment above discusses undertones.