budgetary policy used to promote GDP growth how ?

Budgetary policy of the government includes the estimates of government receipts and expenditure for the upcoming fiscal year. Among the components of GDP, there is Government expenditure and net exports. Government is increase it's expenditure in the economy on public goods, schools, hospitals and subsidies for the poor. Moreover, it can try to implement the policy of 'import substitution' to encourage people to substitute imports for domestic goods. Thus, investment expenditure will increase. All of which will lead to increased GDP when these components of AD also increases.