çıkmak by itself just means 'to go out/to exit' (you can, for example, go out of a room). This is different in meaning than "to go outside" which means that you have to physically out outdoors. Just like in English, you have to include the word "outside" to get this meaning clearly.
Also, "to the outside" is grammatically incorrect. It doesn't make sense in English ("outside" is one of a few words that does take articles and doesn't take the preposition "to" when talking about motion. Another example is "home" :) )