There are several ways to proceed:
Builders usually have some "standard designs" they have recently built. If so, and you find one that you believe is suitable, you should ask the builder if you can see the finished product. Something that looks OK on a drawing may be too small when viewed in person.
Another option is to look at newly built houses in the area/neighborhood you are interested in. By walking through a finished, but unsold new house, you can gain a lot of insight on things you may want to change.
Often, these newly built houses will have a low-detail floor-plan drawing of the design. Take one and show it to your builder. You should also take pictures of the inside and outside of the house.
Another design consideration is whether this house will be your retirement house. Single story, wide doorways, walk in shower, etc are some of the considerations.
Over the years, my wife and I have build 3 houses using the second method. We built our current house 27 years ago, and still love the design. Our biggest "mistake" is not including a 3 car garage. Yes, the kitchen is in need of an upgrade which we will do within the next 2 years.
HTH.
We lucked out because we know someone that does drafting for an architectural firm. They have their own side business and can run things thru an engineer for complicated stuff and get seals on drawings. They charge by the hour (cheap) which allows us to make changes and experiment a little. As we’ve “grown” thru this process, it’s become necessary to look for more reasonable (and smaller) ways to build. Using this draftsperson has been a great way to do it.
Will we get it built? Who knows...