Some cats as they get older need a little help with diet, mobility, and overall care. There are products for that. A senior cat might develop a disease that can be controlled or greatly helped by meds and even diet. Have you seen the array of special diet cat food on the market? There are cat food options for kidney disease, thyroid disease, bladder 
problems, digestive issues, sensitive skin, obesity. There’s even a formula for outdoor cats.
Your older cat might have trouble climbing or jumping up onto his favorite spot on the sofa or your bed. There are ramps and portable stairs to help with that. As cats age some of them get arthritis and find it difficult to climb in and out of a litter box. They actually make litter boxes for older 
cats. Check out litter boxes with lower sides or with a ramp up to the opening.
Some older cats seem to need more warmth in order to be comfortable. They lay closer to the wall heater or fireplace. Offer a cozy cat bed closer to the heat source. Make blanket tents for her to crawl under and sleep. Purchase a covered bed that helps hold in her body heat or a heated cat bed.
Here’s a site with some innovative items designed for the disabled or older cat. https://iheartcats.com/10-must-have-products-for-senior-cats
