Yes, those values control the width and position of the panel. These are set for User Interface Scale 1.00:
"AnchorMin": "0.345 0.110",
"AnchorMax": "0.64 0.150",
Changing the above will affect all players on your server. If you only want to change your own panel, you can use /panelmove (this requires permission).
If you have the Backpack plugin, you can use the settings below (assuming you are using the default Rust UI Scale 1.00):
"AnchorMin": "0.345 0.110",
"AnchorMax": "0.69 0.150",
These are also set for UI Scale 1.00.
Hope this helps! If you're still having trouble, let me know your UI scale and I can adjust the values for you