JSFiddle - React, Tailwind, and code Playground

HTML

<input type="checkbox" id="ckbxEmp" >czech Bachs
<input type="text" id="txtbxSSNOrITIN" maxlength="5">

JavaScript

$(document).on("change", '[id$=ckbxEmp]', function () {   
    
    var ckd = this.checked;
    var $input = $('[id$=txtbxSSNOrITIN]');
    if(ckd) $input.data("oldValue", $input.val() ); // Remember the current value
    
    $input.prop("maxlength", ckd? 2 : 144).css({
        background: ckd? '#ffff00' : "green",
        width: ckd? 24 : 144
    }).val(function(i, v){
        // If checked, slice value to two characters:
        return ckd && v.length>2 ? v.slice(0,2) : $input.data("oldValue");
    });
    
});