JSFiddle - React, Tailwind, and code Playground

HTML

<p>Deliver products every
    <input type="text" id="thisInput_prod1"/>
</p>
<select id="thisSelect_prod1">
    <option value="Days" selected>Days</option>
    <option value="Weeks">Weeks</option>
    <option value="Month">Month</option>
</select>
<p>Deliver products every
    <input type="text" id="thisInput_prod2"/>
</p>
<select id="thisSelect_prod2">
    <option value="Days" selected>Days</option>
    <option value="Weeks">Weeks</option>
    <option value="Month">Month</option>
</select>

JavaScript

document.getElementById('thisInput_prod1').value = '28';
    document.getElementById('thisInput_prod1').readOnly = true;
    var x = document.getElementById('thisSelect_prod1');
    x.options[1].disabled = true;
    x.options[2].disabled = true;

    document.getElementById('thisInput_prod2').readOnly = true;
    var y = document.getElementById('thisSelect_prod2');
    y.options[1].disabled=true;
    y.options[2].disabled=true;