Newbie - counteracting Auto-Contrast

I took footage using my cell phone (Samsung Galaxy 8) - seems there is an Auto Contrast feature. Video was of me using Sign Language. every time my hands move, the Auto Contrast went crazy - video is constantly adjusting it darker/lighter/darker/lighter. How do I counteract that using DaVinci so the footage is a SET contrast. (and for future use -- any ideas how to turn that feature OFF on the cell phone - I can't find settings for this)

call it "UN-Auto-Contrast"

That's your phone using auto exposure not contrast. Almost impossible to correct. Next time set your phone to manual exposure if it has that facility.

i sometimes get decent resualts with "color stabliser" OFX

spend 10$ and buy "FILMICPro" for your phone: is excellent!

Manual frame-by-frame keyframes can do it, provided you have lots of time and lots of patience. The exposure changes are fairly non-linear, so the best you can do is make the results better, not perfect. It's possible if it was a static shot, you could correct it as much as you could and then use De-Flicker to stabilize the moments that fluctuate. But this is a bandaid fix at best.

This is one of those occasions where I need to pull put my T-shirt that has the word TOY CAMERAS and a big red circle and line through it. Cameras like this are just bad for post.

In Resolve Studio there's also the Color Stabilizer OpenFX. I've had good results with it on a drone shot where the camera was in auto mode.