Sure, being addicted to staring at a small screen in your hand means less physical activity and more heart disease. Also, the constant propaganda and focus on negative news can increase cortisol and blood pressure.

Your English is good.

Your English is mostly perfect, but (and as someone who tries, like you, to speak another language correctly):

Could it be that not only these platforms are harmful in mental health and privacy but also physical health?

should be

Could it be that not only are these platforms harmful in mental health and privacy but also physical health?

The change in location of the word are is what makes it a grammatically correct question rather than a statement.

To me, I think the primary harm to our physical health IS the impact on our mental health, which is a physical health. To say nothing of neglecting our physical bodies by being so sedentary.

Is there an increase in the actual number of people with hypertension? Or is there an increase in the known number of people with hypertension in your country? While I don’t want to downplay the risk and frequency of any medical condition, it’s important to consider the increase may come from better, more frequent diagnoses and testing ability. A similar increase in cancer frequency largely came from more frequent screenings, better testing, and more knowledge all around. Yet, all kinds of things were blamed for the “sudden” change from cell phones, plastic, banning lead, vapes, non-organics food, GMO food, to nuclear power plants.