Hi David
There are loads of them.
Randy B Singer frequently recommends "Clipy".
I've use "Jumpcut"for years & years. It is 64bit now, so works with all Macs. These are free and, as I said, there are plenty more (just look in the App Store).
I think one question you should ask yourself is: "what will I use my Clipboard Manger for?"
Is it just text? Photos? Music files? Do I want to edit a clip/add to a clip? Do I want to store clips in Albums or Folders of their own - one for each category or subject matter? Do you want to sync clips across devices (other Macs and iOS devices)?
These type of questions are relevant because you can part with big money to get some amazing apps.
For me, all I want is text (including numerals ie anything a keyboard can generate).
When you've really decided on your needs, search the App Store; do a Google search for "Best Clipboard Managers for Mac", and go through the best articles and see what each app does.
Other members will give you their favourites and that's great; but what I suggest you want is a manager that does exactly what you need, no fuss, minimal expense and complexity
Ian