@DustinB3403 If you (or your customer) are using PRTG, you could use the "cloud ping" and "cloud http" sensors to monitor reachability from around the world. Those sensors will try to reach your website from 5 different AWS data centers, and will report on reachability and response time from each of those data centers. If something goes wrong, you can get an alert, so you know you need to react. The free version of PRTG will let you run 5 cloud http and 5 cloud ping sensors.
If that's not enough, check out services such as https://www.site24x7.com/, which provide similar ongoing monitoring on a larger scale.
If a one-time or manual test is enough, check out services like https://tools.pingdom.com/ or https://www.webpagetest.org/, which are free and don't require any setup on your side, but only provide a snapshot of up/down at the time you try them.