chest like arms has a lot to do with genetics make up,,
guys with good chest will have hard time to develop real big arms,,guys with big arms will have hard time to develop impressive chest,,
guys who have both and no problem developing both are usually on stage wearing underwear
and winning shows
guys who have good chest genetically will be able to grow and develop it with 2-3 45lbplates each side of the bar and look like (chest wise) they can do 5 plates each side of the bar,,
guys who have good arms genetically,,wil be able to develop them to 18 inches doing 40-50lb dumbells,,
to your question,,
when start training flat bench is a must,,
during the years when you develop a good base and foundation,,i would limit flat bench and do a lot more incline bench,,
incline bench is the key for swole,,thick,,full,,chest and front delts