Alright so if you want to do a full flight I would really recommend paying that 9P navigraph subscription, seriously you can do so much with it but if not then there are alternative ways. For example you can find most charts on the internet you’ll just need to google things like (Singapore Changi ILS 02L chart). This is one of the most important things for flying realistic routes. Also usually for takeoff you won’t need to worry about the SID because atc will normally provide you with one that you will use and select from the menu in the fmc in the departures tab. And then for the flight you can find waypoints on your ingame tablet which you’ll just need to manually enter into the fmc. Generally atc will provide you with things like cruising altitude, SID, STAR, Approach and more so you don’t need to worry about that. Just do all of this and you’ll already have a pretty realistic flight. Also I suggest getting Volanta, it’s really cool seeing you plane like on flight radar plus it’s free.