Optimal Split?

Been on a cut for a while now and I’ve lost about 40-50 lbs. I am currently 5’10 at 157 lbs. I got a DEXA scan done recently, and I was surprised to say the least. It said I was 21% BF, which is lower than I expected, but my arms are in the 2nd percentile in terms of lean mass, while my legs are in the 87th percentile. The legs makes sense because of all the weight I was carrying, but my arms being so weak is not something I expected. I only recently started lifting properly (2-3 months), and have been seeing some results. I’m currently doing a full body 3 days a week split, with 5 days a week of cardio on top, but I feel like I should follow a split that emphasizes my upper body (especially arms) a lot more. Any recommendations for a 3-4 days split? My goal right now is hypertrophy and maybe definition, not strength.