AT&T does offer additional discounts to older adults with an AARP membership ... T-Mobile Unlimited 55+ plans start at $45 per month for a single line or $60 per month for two lines ($30 per line).
You’d be surprised at how many in-store incentives there are that you won’t find online— and not just deals on cellular services, but also seniors-only discounts on groceries ... and McAfee Security ...