where do i actually find the clipboard on my android phone?

Heads up that Gboard only keeps clipboard items for about an hour. If there's something you paste all the time, long-press it in the clipboard and pin it, pinned ones stay.

It's in the keyboard, not the phone settings. On Gboard tap the clipboard icon in the toolbar above the letters (turn it on the first time). Samsung's keyboard has one too in the toolbar. Long-pressing a text box and hitting Paste only gives you the last thing you copied.