Do we need a cellular plan if the Watch SE is used only for date, time and emergency SOS calls?

Of your Fahrer is using an iPhone and has it wothin 20 m Range it will not be necessary to have a Plan. However of iPhone is not to be Carrier I would recommend a basic LTE plan just for all funcions to be active. After all it is about his safety. Without the lte Module with a plan the iPhone Must always be within 20m eange and with elderly people that is not always an obvious thing.

i would recommend LTE westchnął SE with a basic plan

if he have an iphone within range of the watch the gps only apple watch will work just like the cellular model using the phone for cellular data

Having gone down similar paths for some other people, some considerations…

I’d consider another solution and preferably one with a longer-life battery, if there is a likelihood the person might be forgetful around wearing and about charging the Apple Watch.

If eyesight is possibly an issue, it’s also potentially harder to see and harder to control Watch. Including for making an emergency call, or for cancelling an unnecessary or mis-detected call.

And if you really do want to go with Apple Watch here, and particularly with no paired iPhone, get the cellular model and use Family Sharing to manage it.

Particularly if there is no Wi-Fi, or if Wi-Fi is unreliable, check whether local cellular coverage in the residence and nearby is adequate for Apple Watch, too. Watch cellular might not be (is not) as sensitive or as powerful. If Wi-Fi coverage is available and reliable inside the residence, this is less of a factor.

Fall detection requires a comparatively hard fall, and—though probably not an issue for this case—some activities can produce erroneous fall detections.

Watchq1 wrote:

Thankyou but what if he does not own an iPhone either (he is frail). Can the cellular watch still send a text or emergency call? Ie him not speaking into it but an auto emergency call

Based on your descriptions, I do not think an Apple Watch is the ideal solution for your father.

It might be better to get a professional health monitoring service. My Mother-in-Law had one.