@KingOmar11_ If some areas can't be closed, I personally add a sphere, and make a boolean operation(布尔运算), and then resculpt that part.
If you plan to add eyes or use it to make a bjd, then re-shell it, the internal structure is roughly as shown in the picture.
@KingOmar11_ You sculpted so many cute expressions, that's amazing! If I understand you correctly, the remaining steps should be easy for you. If it's not solid , close up holes(封闭孔洞) first.