A Study to Investigate the Efficacy and Safety of Dato-DXd With or Without Osimertinib Compared With Platinum Based Doublet Chemotherapy in Participants With EGFR-Mutated Locally Advanced or Metastatic Non-Small Cell Lung Cancer

* Histologically or cytologically confirmed non-squamous NSCLC.* Must have evidence of documented pre-existing EGFRm information (EGFRm known to be associated with (epidermal growth factor receptor \[EGFR\] tyrosine kinase inhibitor \[TKis\] sensitivity \[Ex19del, L858R, G719X, S768I, or L861Q\], either alone or in combination with other EGFR mutations, which may include T790M). * Documented extra-cranial radiologic progression on prior osimertinib monotherapy (as most recent line of treatment) in the adjuvant, locally advanced, or metastatic setting. * Less than or equal to (\<=2) prior lines of EGFR TKIs (osimertinib is the only permitted prior third generation EGFR TKI). * At least one lesion, not previously irradiated, that qualifies as a RECIST v1.1 TL at baseline and can be accurately measured at baseline. * World Health Organization (WHO)/Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. * Adequate bone marrow reserve and organ function within 7 days before randomization.