It very much depends where you are m and the specific hotel, as to what you get and the choice.
Dh and I are currently at an all inc hotel. First one we've done for years, but felt in covid times for long haul it was easier this year.
We have a choice of 8 restaurants and a number of bars and snack places.
Not all are open for every meal and not every day. All restaurants seem to have one closed day. One is reservation only but included in all inc. There are set me ha and al a carte but all is included. There isn't different tiers of all inc here so no costs in too or added extras ti access 'better' food. Our choices range from burgers and chips to lobster, sushi and live cooking tappenyaki.
All drinks inc premium brands are included. This is with all meals, waiter service at the pool, in your room and at the bars.
All snacks are included from cakes and biscuits to ice creams and crisps to mini chocolates and macrons etc. Available from snack cafes and bars.
In room we have a mini bar which is stocked daily. In a cupboard we have three full size bottles of spirits and wine. These are replaced when empty. The minibar also has chocolates and snacks.
Room service for meals and drinks 24 hours a day is included too.
Actives and entertainment is included. The water activities inc for free are non motorised sport, shirking equipment loan and the basic scuba lessons. Paid for you can have boat trips, accredited scuba lessons, and excursions.
When booking you can normally find out what it includes by visiting the hotels own website.