I find raglan cardigans stylish on and off-season, and it is the style of cardigans many people struggle to make. They are very versatile and personal, be it a baby sweater or an adult sweater. One of the things that most people struggle with is the yoke. The yoke is the upper part of the body. Once you get the yoke right, the armholes shape themselves.
The yarn craft council has a measurement that one could use as a guide. check out the guide here https://www.craftyarncouncil.com/standards/baby-size-chart .One of the best ways to try out a new cardigan design is to make it small first. When you get it right then, you can make it in a bigger size.
A useful tip when making raglan sweater cardigan use the measurement of the head circumference Add 4″. The figure you get should always be divisible by 4 for example a circumference of 20″+4 =24. This means that each side gets 6″ with the side with the opening being divided by two to get 3″ because is the front part that has an opening . If your raglan sweater cardigan has no opening then it will remain as 6″.
I found this measurement on Pinterest, very helpful I will be making a second second sweater from this formulae.