ok - try going in to the keyboard settings and make sure the " Keyboard toolbar " option is turned on - when you open the keyboard you should then see options on the strip at the top of the keyboard ( where it shows the word options when you are typing ) again as long as you haven't typed anything yet - then try the 3 dots again
Think will prob be the Samsung one set as default but if you go in to the phone settings - general management and scroll down a bit you will ( hopefully) see an option for default keyboard and also an option for Samsung keyboard settings where you can turn on the keyboard toolbar
Not sure but think would be Samsung Did you manage to find the setting for Keyboard Toolbar and make sure it was turned on ? Also what phone / UI do you have ? Mine is a Note 10 + - maybe the settings you need are somewhere else in the menus if you have a different model
One other thought - if you have got the keyboard toolbar turned on then when you open the keyboard ( again before you type anything ) you should see a few icons on the strip at top of keyboard - if you do one of these may be for the clipboard already and then you wouldn't need to press the 3 dots - the 3 dots display additional tools options for things not already shown on the top strip
Sorry kenl - can only suggest either going in to the phone settings and try using the search function to find keyboard toolbar - or a search on the Internet - or maybe have a look at installing Googles Gboard keyboard from the Playstore which I believe also has clipboard access - sorry not able to help you