If I accidentally downloaded a malicious 'read comics free apk', what steps should I take?

If you suspect a malicious APK, immediately disconnect your device from the internet. Run a full scan with a reputable antivirus app. Change your passwords for important accounts (email, banking, social media). Review app permissions and revoke any suspicious ones. Consider a factory reset of your device as a last resort, after backing up important data (but be cautious about backing up potentially infected files).