This is a complex question to answer, but the simplest answer is that if a child is not functioning at their ‘potential’ (due to cognitive problems in a particular domain) then it is often possible to address this: but they still may not reach the level of a child with a higher degree of natural ability. There are training programs that target ‘Working Memory’ and boost a child’s ability to hold information in mind and mentally manipulate it: and there is also evidence of improvements in a child’s ‘Working Memory’ if children with ADHD take stimulant medications.
If there are problems with language skills, these can often be improved with increased exposure to the English language, correcting any hearing problems, and addressing speech problems. There are some studies that have shown the benefit of training children in problem-solving methods, and other studies that have shown the benefits of certain types of video games in terms of visual-spatial skills, but these findings are not always consistent.
IQ is different to a child’s academic achievement. If a child is performing academically below what is predicted from their IQ, then there are interventions that addresses literacy, numeracy, emotional coping, social skills, and self-esteem, which will in many cases have a benefit in terms of boosting the child’s academic performance.