How does the wool weight effect the pattern?

Hi! I’m a beginner knitter and have some 100g wool that I wanted to try use to knit a little winter hat for my daughter(almost 1 year old). but the pattern I’ve found recommends 50g. What will happen if I do it with the 100g?Will it be bigger so I should do less stitches? Should I ditch the plan and buy new wool or try find a new pattern? Maybe I’m making it all too complicated! Thanks!