An open, glossy crumb comes from three things: enough gas production, enough dough strength to hold that gas, and gentle handling that does not pop the bubbles. Hydration helps, but it is not the main lever; many wet doughs still bake dense.
The real keys are an active, well-timed starter; fermentation that finishes in the shaped loaf rather than in the bowl; and folds that build strength without degassing. Stretch and fold three or four times in the first hour, then leave the dough alone.
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Cut the loaf with a sharp serrated knife once cool, not before; cutting warm bread smears the crumb. If the crumb is dense but the flavor is good, the fix is timing, not water.