Generally an experienced rider has established their position on the bike based upon effective power output and handling needs. While bike geometries may have changed along with materials, the position of the saddle and hands need not change. The variety of bars, seatposts, stems, and spacers make possible the adaptation of a bike to a riders preferred postion.
The same variety, though, can be a challenge to the newer rider who has yet to establish a riding position as all the chioces simply make for confusion. Ths site is full of riders asking for advice on how to understand and manage position and cockpit size. The consequent discussions are like chasing one's tail with the panoply of beliefs and "what-you-otta-dos" expressed all without ever seeing the OP on an actual bike.
I would suggest asking around your area for someone to fit you on your bike. Estalishing just who is an actual authority is a subject for a long and chaotic thread with little concensus. A "good" bike shop can get you close as can a highly experienced rider friend or coach. After that there are any number of "experts", either with a plumb-bob and tape measure or a computer to achieve a fit. I have found them all very useful for myself, my son, and my teams.
I do a pretty good fit myself within 3 mm of cleat position in a susequent computerized fit for my son. Yet I have the advantage no fitter has: I ride with these guys all the time, often next to them as they ride, and see the effect of their position and nudge things to where I think they need to be. It takeas a lot of time.
It is important to understand that there are no guarantees or absolute truths. Anyone trained to fit, in whatever method, believes in a specific goals as truth. Further, fit changes with skill, stamina, and the fitness during your season. That fit is so challenging doesn't mean it should not be attempted.
You would do well to research fit in your area and make a start. From there you can make adjustments.