It can vary slightly from area to area and there should be an individual assessment for each client in line with their needs and preferences. In general though, if he's having 3 visits a day I would expect that to be one visit in the morning in which he'll be helped out of bed, helped to shower/wash, toilet and dress as needed, fetched breakfast (usually just cereal or whatever's quick), a drink and any meds he needs, then settled wherever he spends the day. The carer may perhaps do a quick wipe around the kitchen, stick a load of laundry on or spend a few minutes having a quick social chat, depending on how long the first part takes. The middle visit will probably be either lunchtime or tea time (or an unhelpful middling timing) and be very short, maybe as little as 10-15 mins and just enough time to make a cup of tea and a sandwich or stick a ready made hot meal in the microwave for his dinner (if they have a hot meal at lunchtime they can also prepare a sandwich for his dinner, or vice versa). Perhaps there will be time to put the morning laundry on to dry and/or wash his breakfast and lunch things up during the middle call. The 3rd call will usually be a 'put to bed' call and will be helping his undress and get ready for the evening. Again there may be time for some brief cleaning, washing up and tidying tasks at this call as well.
So you get the picture, main priorities are washing, dressing, toileting and meals, there may be time for them to do some household or cleaning tasks and general social chit chat, but often very limited depending on how able he is to do the first parts for himself - unfortunately with social care time and funding being so very limited keeping body and soul together in the most basic way has to take priority. Food usually has to take no longer than 5-10 mins to prepare so cereals, sandwiches, ready meals are the order of the day (carers often have quite varied cleaning skills IME, many will happily knock up quick things like scrambled eggs, omelettes, pasta and sauce etc others not at all!). The carers are unlikely to have time to do a full clean of the house, gardening, take him to the shops or for a walk or similar, anything that takes longer than 10 mins or so is usually off the table.
So if you have time and/or money to spend helping, I would focus on: sorting out food deliveries, ideally including lots of quick/easy cold options and some nice ready meals - companies like Wiltshire Farm Foods are very much set up for the elderly market and I think will even help unpack and put away if needed. If you/he can afford it a regular cleaner, gardener and laundry service are extremely helpful, or otherwise you and other family may have to do these things as and when you can make it to him and accept there may be some decline in standards. Do see if you can tap into local volunteer networks, there may be 'befrienders' who can come and keep him company occasionally or groups he can join or similar, and there may be people who are able to do errands like popping out to collect prescriptions (although these can usually be delivered), taking him to appointments (although patient transport may be available) or helping with deliveries which were the sort of things I found a nightmare when I was in a similar situation with my Mum as you couldn't get carers to do it but not really worth a trip all the way out there myself! Good luck