Hello I have the following design in DESeq2: ~GT+TP+TP:GT . GT has two levels (K,W) . TP has two levels (0,2). I am looking for the genes that are up-regulated in samples where GT=W and TP=2. How do I define the contrast that these genes will have the highest log2FC. Thank you

First, see the vignette section on interations, and the examples in ?results.

Beyond that, if you have further questions, setting up the statistical design is important. It's worth meeting with a local statistician or someone familiar with R to help you in this step. Unfortunately, I have to restrict my time on the support site to software related questions.