Universal Clipboard is not an app.
Handoff can be turned on in your settings: General - Handoff, enable it.
Handoff and Universal Clipboard allow starting to work on one Apple device, then continuing and finishing the same work on a different Apple device, e.g.
When two of your Apple devices are close to each other, and you copy something on one of them, you an paste it on your other device. It will be available for pasting for a short time.
Highlighting in Safari can be tricky. For sentences and paragraphs I usually have more luck selecting the last work and expanding up. No idea why. I assume it’s a bug and will be fixed eventually.
Sometimes selection freaks out and own’t let you do much of anything. Refeshing the page usally fixes this. It happens a lot on this forum when you go in/out of edit mode. Another bug, most likely.
Not all web pages will let you select and copy. I don’t know what the criteria is, but it’s a website thing that Safari is honoring rather than Safari itself making the decision.
If you can select the word at all, then it is probalby not the website blocking, but a bug/problem in Safari. Refreshing the site will sometimes fix this, temporarily.
It’s when you can not even select a word that the website is probalby blocking. Usualy it is just images and/or vidoes they are trying to block, but sometimes blocks of text will be uncopyable
Sometimes you can get around it by selecting something that can be copied, and expanding the selection around the blocked image and/or text. And sometimes not.
Is it a specific website, or a variety? If you don’t mind sharing the sites (and I don’t have to sign up for anything) I”m willing to take a look and see how they work for me.
No problem. Good luck.