How can I watch old family DVDs on my Mac Pro?

There are also lots of other portable USB CD/DVD burners whose descriptions say they will work with Macs. These go for about $16 – $30 online (before tax and shipping). Many are no-name, although there are brand-name ones, from LG and Asus.

Some want to grab power off two USB ports, so be sure to investigate that if it matters.

Exactly which Mac Pro do you have? The current 2023 model (in silver):

may have different ports than the previous 2019 Mac Pro and require a USB port adapter.

I concur with Servant of Cats that the OWC self-powered drive is the best for reliable performance. Those models powered by the computer's USB port ("bus-powered") are often not as reliable.

Or do you have a MacBook Pro laptop? The similar names cause a lot of confusion around here.

when you get an optical drive you can download vlc player it's a free player which will play most formats

This is the drive I bought for my current Mac:

Other World Computing – 24X OWC Mercury Pro USB 3.2 (5Gb/s) Super-Multi DVD/CD Burner/Reader External Optical Drive with M-DISC Support

It's a desktop drive with its own power supply. The included USB 3.0 B to USB-A cord is very short, but can easily be replaced with a longer USB 3.0 B to USB-A, or USB 3.0 B to USB-C, one.

Other World Computing has a portable, bus-powered OWC Slim USB 3.2 External Optical 8X DVD/CD Burner – but that one may want to be connected to two USB ports so it can grab more power than is available on a single USB 3 port.

Sequoia includes a DVD Player application. These days, instead of being in the main Applications folder, it is hidden away, but it is still there. You can launch it by inserting a DVD-Video disc or by searching for it using Spotlight.

Blu-Ray (which Steve Jobs once likened to "a bag of hurt") is a different matter. macOS doesn't include anything to play Blu-Ray movie discs, and most CD/DVD/Blu-Ray burners don't come with such applications. You would need to look for a separate Blu-Ray player application.

macOS no longer includes anything like iDVD for authoring home video discs, but I believe that there are versions of Toast that can author home DVD-Video and Blu-Ray video discs. If you want to duplicate a home video DVD, I think you can do that using Disk Utility (to create a .DMG) and Finder (to burn new discs from it). (That wouldn't work for encrypted commercial movie discs. You'd be blocked from creating playable copies, one way or another.)

An optical disc drive: How to connect the Apple USB SuperDrive - Apple Support

However, Apple finally stopped selling them last year. You can find them on the used market.