Sometimes a SharePoint column has too much information, which eventually stretches rows and distorts the look. An example below is a Multiple lines of text type column:

This simple JSON code is useful to hide noncrucial information, while still allowing easy access to that data by hovering your mouse cursor over it.

{
  "$schema": "https://developer.microsoft.com/json-schemas/sp/v2/column-formatting.schema.json",
  "elmType": "div",
  "style": {
    "display": "=if(@currentField, '','none')",
    "font-size": "12px"
  },
  "txtContent": "Hover to see more",
  "customCardProps": {
    "formatter": {
      "elmType": "div",
      "txtContent": "@currentField",
      "style": {
        "padding": "5px 5px 5px 5px",
        "border": "solid",
        "border-radius": "2px",
        "border-width": "1px",
        "box-shadow": "0 0 2px 0"
      }
    },
    "openOnEvent": "hover",
    "directionalHint": "bottomCenter",
    "isBeakVisible": false
  }
}