Plan a full race across swim, bike, run, transitions and nutrition. Pick the race distance, then work through the tabs.
Use your current critical swim speed (CSS) pace, not pool PB pace. Open-water swimmers rarely swim the straight-line distance, hence the sighting allowance.
Ironman transitions include long runs through change tents; 4-6 minutes each is normal. Short-course races are much quicker. Defaults update when you switch race.
Typical race targets: 80-120 g/h carbs on the bike (gut-trained), 50-70 g/h on the run, 500-1000 mL/h fluid and 500-1200 mg/h sodium depending on heat and sweat rate. Practise the full plan in training. Not medical advice.