The experience I got from this job has strong contributions in changing my character from employee to leader.
This is a word that has been borrowed from English and is now used in Indonesian as the noun kontribusi. However, it’s difficult to find a verb that collocates with the noun contribution in English. Certainly you would not use ‘have‘ + ‘contributions‘. In English, contribution usually appears before the verb, as the subject of a sentence. In addition, contribution (subject) often refers either to money or to the efforts of a person or people. In the example above, however, experience and changing are both abstract nouns where one is the cause and the other is the effect.
If you want to communicate cause effect then you need the verb form contribute. There are still collocation issues, but heck – that gives you something to show off in your IELTS writing, right?
Remember that when both nouns are abstract, contribute to behaves as a cause effect signal. This is a relatively low-frequency signal and is therefore a good signal to use in IELTS writing as an alternative to the more common verb cause.
Contribute to is also weaker than cause and is therefore useful when you want to express less than 100% certainty:
Using weak verbs is one of several strategies for weakening debatable claims. I deal with other strategies in other posts. You can find two more strategies here.