In general, it doesn’t really matter what you eat on OMAD, save for the obvious things to avoid like refined sugars and processed carbohydrates. However, since this is the OMAD Keto subforum, I’ll adjust my answer appropriately.
Is rice good or bad on OMAD Keto? Well, it’s not just bad—it’s awful. When doing keto, you want to keep your carbohydrate intake to below 50g a day, but ideally around or under 20g. A 100g serving of standard white rice is going to have 28g of carbohydrates, which is already going to send you way over the ideal limit.
Rice, oats, flour, pasta, bread, fruits, and starchy vegetables are all foods you have to avoid on keto due to them being extremely dense with carbohydrates.