Conditional Formatting

johncamp08 

This example should get you started. The key is the formula shown on line 8 which uses the if function to turn on special classes if the comparison returns true.

{
    "elmType": "div",
    "children": [
        {
            "elmType": "span",
            "txtContent": "@currentField",
            "attributes": {
                "class": "=if(addDays([$SurveyDate],6) < [$InstallDate],'sp-css-color-RedText sp-field-bold','')"
            }
        }
    ]
}

To learn more: https://docs.microsoft.com/en-us/sharepoint/dev/declarative-customization/formatting-syntax-reference#expressions 

Good Luck,

Don 

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