Follow the below steps:
1. Create slicer of the field required.
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2. No go to Format tab and go to Items as below
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3. Change the background color as required and change the font size.
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4. Now change the object size vertically.
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5. Go to General and change the orientation to Horizontal.
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You would get a slicer like above in the form of buttons.
Change the background, font color, and size as per requirement.
Hope it helps you!