If you need some specific shipping title change, then use the below method

For Ex. Priority Mail 1-Day instead of Priority Mail (2-3 Days)

Firstly, you need to add the following file.

1. Create file di.xml on app/code/Magemonkeys/UspsShipping/etc

<?xml version="1.0" ?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
   <preference for="MagentoQuoteModelQuoteAddressRateResultMethod" type="MagemonkeysUspsShippingPluginModelQuoteAddressRateResultMethod" />
</config>

2. Create file Method.php on app/code/Magemonkeys/UspsShipping/Plugin/Model/Quote/Address/RateResult

<?php
namespace MagemonkeysUspsShippingPluginModelQuoteAddressRateResult;

class Method extends MagentoQuoteModelQuoteAddressRateResultMethod
{
    public function setPrice($price)
    {
        if (strpos($this->getMethodTitle(), "Priority Mail 1-Day") !== false) {
            $this->setMethodTitle("Priority Mail (2-3 Days)");
        }
        $this->setData('price', $this->priceCurrency->round($price));
        return $this;
    }

} ?>