I want to make one three seater and 2 single seaters. the dimensions of the same are attached.
If you are planning to make your own furniture (or cabinetry or anything with wood) then learning how to calculate the stock needed is a skill YOU need to learn.
Question about woodworking are better served on the woodworking stack.
There is a wealth of info for you to research on internet websites or YouTube to learn these skills. If you find you are stuck and need a particular question answered then post your question and explain how your research as not yielded the info you need.