how to target an index with insertrowafter code example

Example 1: getranges google script

let SS = APP.getActiveSpreadsheet();
let sheetIndex0 = SS.getSheets()[0];

sheetIndex0.getRangeList(['A1', 'B1:C7']).setHorizontalAlignment("center");

Example 2: google apps scipt getRange

getRange(row, column, numRows, numColumns)