If you just want to show the data in text column in list view, you can use below JSON code:
{
"$schema": "https://developer.microsoft.com/json-schemas/sp/v2/column-formatting.schema.json",
"elmType": "div",
"txtContent": "[$PeoplePickerColumn.title]"
}
Make sure you are using correct internal name of your People Picker field in txtContent
. You can get the internal name of your column by following this article: How to find the Internal name of columns in SharePoint Online?
Microsoft documentation: Use column formatting to customize SharePoint
If you want to store the actual value in text column, it is not possible with JSON formatting.
To populate the value in text column on list item creation/update, you have to call a power automate flow & perform update operation.