A Study to Test Whether BI 1839100 Improves Cough in People With Idiopathic Pulmonary Fibrosis or Progressive Pulmonary Fibrosis

Inclusion Criteria For Idiopathic Pulmonary Fibrosis (IPF) cohort: * Minimum age: 40 years * Diagnosis of IPF * Chronic cough (\>8 weeks prior to Visit 1) attributed to IPF and refractory to treatment for known causes (Principal Investigator (PI) assessment) * Cough Severity visual analogue scale (VAS) ≥30 mm at Visit 1 and Visit 2B * Forced vital capacity (FVC) ≥45% of predicted normal at Visit 1 * Diffusing capacity of the lungs for carbon monoxide (DLCO) \>25% of predicted normal at Visit 1 * Patients may be either: * On stable therapy with nintedanib or pirfenidone for ≥12 weeks prior to Visit 1 and are planning to stay on this background treatment for the whole trial duration. Combination of nintedanib plus pirfenidone will not be allowed * Not on therapy with nintedanib or pirfenidone for ≥12 weeks prior to Visit 1 (either antifibrotic (AF)-treatment naïve or previously discontinued) and do not plan to start or re-start AF treatment during the trial. It is not permitted to delay nintedanib or pirfenidone therapy for the purpose of participating in this trial * Patients aged ≥40 years when signing the informed consent For Progressive Pulmonary Fibrosis (PPF) cohort: * Minimum age: 18 years * Diagnosis of PPF * Chronic cough (\>8 weeks prior to Visit 1) attributed to PPF, refractory to treatment for known causes (PI assessment) * Cough Severity VAS ≥30 mm at Visit 1 and Visit 2B * FVC ≥45% of predicted normal at Visit 1 * DLCO ≥25% of predicted normal at Visit 1 * If receiving immunomodulatory therapy for interstitial lung disease (ILD), allowed medications include tacrolimus, mycophenolate mofetil, or azathioprine (stable dose for 12 weeks prior to Visit 1) * Patients may be either: * On a stable therapy with nintedanib for ≥12 weeks prior to Visit 1 and are planning to stay on this background treatment for the whole trial duration * Not on a therapy with nintedanib for ≥12 weeks prior to Visit 1 (either AF-treatment naïve or previously discontinued) and do not plan to start or re-start AF treatment during the trial. It is not permitted to delay nintedanib or pirfenidone therapy for the purpose of participating in this trial * Patients aged \>18 years when signing the informed consent Further inclusion criteria apply. Exclusion criteria for IPF and PPF cohorts: * Acute exacerbation of IPF/PPF within 12 weeks prior to Visit 1 * Forced expiratory volume in 1 second (Forced expiratory volume in 1 second (FEV1))/FVC \<0.7 at Visit 1 * Known reversible airflow obstruction/response to bronchodilators * In the opinion of the Investigator, other clinically significant pulmonary abnormalities, including primary bronchitic and bronchiectatic disorder * Upper or lower respiratory tract infection within 4 weeks prior to Visit 1 * Ongoing chronic pulmonary infection (e.g. mycobacterial or fungal disease) * Current smokers (tobacco use within the 6 months prior to Visit 1) * Initiation or change in supplemental oxygen requirement during 4 weeks prior to Visit 1 Further exclusion criteria apply.