Is the company entitled to assign the employee additional duties not stipulated in the contract without financial compensation, especially if they fall within the scope of his original work as an "IT specialist"?

A condition for ijarah (leasing, of which employment is a type) is knowing the benefit for which the contract is made, in order to prevent disputes. The benefit is known either by stipulation or by custom and common practice. If custom becomes unclear, then clarification is necessary; otherwise, the ijarah is void due to ambiguity. Based on this, what experts say regarding the nature of the questioner's job determines whether training on computers is part of his job. If it is, then he is obligated to do it. Otherwise, he is not obligated and has the right to refuse, unless he is compensated for it.