When having both ipf and copd, what are the risks of 30% lung function?

High risk: You probably referring to pft test for fvc, fev1 - which correspond to severe disease. You have increased risk of progressive worsening of lung function, pulmonary hypertension, low oxygen level with need for supplemental one, right sided heart failure, episodic exacerbation, increased risk of pulmonary infections, worsening nutritional status - cachexia, cardiac arrhythmia ( atrial fibrillation.

Respiratory failure: The level of lung function is low enough that respiratory failure can occur with a flare up or an acute infection such as bronchitis or even a cold. Decide ahead of time what treatment you would be willing to undergo if your lungs can't support you. Would you go on mechanical ventilation? If so, for how long?