The manual is here: Kero Kero King (PSX) Manual : Free Download, Borrow, and Streaming : Internet Archive
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I play New 3D Golf Simulation series which I think taught me most about a lot of this, so I just expected Kero to have the normal golf controls.
Probably a golf book or manual or some other golf game would teach you how to change power and expectations when shooting to higher/lower ground, against wind, to use curve left/right to your advantage (draw/fade) etc.