RSS (Really Simple Syndication) is the best way to keep tabs on things online. While social media sites have tried to replace it, it is still the best way to consoooome content, even on social media sites.
For all basic blogs and smart websites, RSS feeds will be obvious and sometimes your browser will automatically detect them, but here is how to get RSS for some common social media sites.
Thankfully, YouTube still has RSS feeds, albeit very hidden ones: for example, mine is https://www.youtube.com/feeds/videos.xml?channel_id=UC2eYFnH61tmytImy1mTYvhA, where my channel ID (starting with U).
All YouTube channels have channel IDs that you can either see in their channel page URL, or which you can find by looking at their page source and looking for something like channel_id.
To "subscribe" to a channel via RSS, just take that channel ID and put it in the format of mine I gave above. The main link goes directly to the video page and I usually stream/download them directly with mpv and youtube-dl.