Buy an external DVD optical drive. There are very many to choose from if you google "optical drive macOS USB" starting at about $20 US.
Amazon sells many. OWC/macsales has several and they are a go-to retailer for Mac accessories and knowledge.
If you get one with the ubiquitous USB-A connector, you'll also need to buy a USB-A to USB-C adaptor or cable to connect to the newest Macs.
If these DVDs are playable in a set-top DVD player, like any commercial movie DVD, then you'll also need to use an app such as Handbrake for Mac to rip your home vids. If the DVDs just have the vids as files in folders, then you won't have to rip them, you can simply click, copy and pst the files to your Mac.