Start with the person's own demonstration
Ask which items they want to reach without assistance and where they can comfortably retrieve and return them. Use an ordinary task such as making breakfast, not an abstract judgment about shelf height. A reachable mug, bowl, and favorite breakfast item can be more useful than reorganizing every cupboard at once.
Check the whole movement
Check the arrangement in use. A low shelf can still be awkward if a heavy box blocks the front. Let the person choose between workable locations, and leave enough clear space for them to return the item as easily as they can take it out.
A lower shelf may still require someone to move a heavy box, lean awkwardly, or hold a door open while carrying an item. Watch the complete sequence with their permission and ask which part creates difficulty. Offer alternative locations and let the person choose how they want their daily items arranged.
Keep the arrangement usable over time
Explain the new locations to everyone who puts things away. Test again after a normal shop or after other supplies return to the cupboard. If items start blocking access, change the placement of the blockers rather than expecting the person to ask for help each morning. Keep private belongings under the owner’s control throughout the rearrangement.