Your course of action really depends on how much work and effort you can put into the expired domain. If you're barely able to maintain and optimize your current site, you probably want to just 301 redirect the old site (note: see my amended comment above about the link value not likely to be passed). If, however, you're more creative and have some time on your hands, you can try your hand at crafting a microsite. If you really know your stuff and are experienced at making money off various websites, you'd probably do well with the third option.
If you bought the domain name, the typical procedure is to unlock the domain name, then either push it to your account at the same registrar (such as https://www.domainsherpa.com/how-to-push-a-domain-name-at-godaddy-com/) or send you the authorization code so you can transfer the domain name to a different registrar (https://www.domainsherpa.com/how-to-transfer-a-domain-name-to-another-registrar/).
Lets look at some settiings, so you could enter a list of websites to crawl for expired domains on, or you can enter a search query say you're looking to form a pbn to boost your money site, that's about horse riding or something you could put horse riding down there and then it'll search, Google for horse riding and then crawl all the domains that Google brings back to you. Then we've got endless crawl and you basically you put in a few seed websites and then it will just crawl endlessly from those websites. So it will take all the domains off those websites. First they'll check whether they're expired or not. If they're not expired, then it'll start crawling them and then it will crawl the ones it finds from them and so on so on and so on. It will just keep going ok.
Finding good aged high DA domains with natural links for SEO and filtering them through our expired domain tools is really easy. Contact us with your SEO or PBN needs to receive an offer. If you need domains for a private blog network, 301 redirects or other SEO strategies, then contact us!. Our pool is huge but so many domains are being bought that it’s diminishing at a fast rate.
Answer: Many auction sites will allow you to backorder the domain name for free. Follow the process above to find the domain name registrar and auction partner site. Then sign up for an account at the auction partner site and enter a backorder. But remember, the domain name may transfer to another registrar at some point so refer to Step 1 above periodically.