Can a ransomware attack on a Windows PC affect other local profiles on the same computer? Can the ransomware attack also encrypt files stored in Google Drive on those other local accounts that were not open at the time of the attack?

Yes, a ransomware attack on one profile of a Windows PC can potentially spread to other local profiles on the same machine if they are accessible. However, it is less likely to directly encrypt files on Google Drive accounts that were not open or synced with the infected machine, unless the ransomware gains access to the Google Drive account through the infected PC or if the account is linked and synchronized with the infected device.