If you’re using modular cabinets then you’ll need to get a list of the cabinet sizes that are available to you and design you kitchen using the cabinets in that list. If you’re going with fully custom cabinets then you have quite a bit more options available to you.
The sink is the most complicated thing to relocate. First, there are usually two pipes supplying it with clean water, one for hot and one for cold. Then, there is a drain pipe that channels the dirty water away. There is also usually an outlet underneath the sink to supply the garbage disposal and dishwasher with power.
The refrigerator, the sink, and the stove, are often the most used areas in the kitchen. So, the distance between them is important because you’ll be frequently walking back and forth between them.
It helps to make the kitchen easier to work in if things that are commonly used together are grouped together in the same general area.