Regardless of which diet strategy you follow, plant-based/high-carb/low-fat; or ketogenic/low-carb/higher fat; or one of the diets in the middle, I think it is a good idea to count calories for as long as it takes for you to recognize what one portion looks like. You will always underestimate your caloric intake by eyballing it, at least until you have the experience of keeping a food journal for at least two weeks.
You have to be honest with yourself. You will need measuring cups and a food scale. the good news is that everything that is packaged already has the calories listed on the label. Some more good news is that there are several free phone apps that you can use for this. The apps have more functionality with paid premium versions. Below are the top four apps from this article.
It will be slow at first, because you have to enter everything you eat, but it gets easier because the app remembers your previous entries, and if you’re like most people, you eat the same things frequently.
If you don’t like using a phone app, then do it the old fashioned way, with a food journal and a pen, like this one, which allows 60 days of recording, which should be plenty.