A high level of suspicion towards the safety of third-party installations still remains because once you randomly click to download unknown files, they may pose potential risks to your device. My first advice is to refrain from using apps from unknown sources. Or you can use another device for your personal account in it like the #2 answer. If your device still contains apps from unknown sources (for compulsory reasons), here are some tools to help you verify whether the file is harmful or not (It is for reference only, because I just synthesize from the internet):
VirusTotal
VirusTotal is an online website used to analyze suspicious files or URLs and detect malware, viruses, worms or other kinds of malicious content. However, a drawback of VirusTotal tool is that it only analyzes the file size under 128MB. To scan a file or URL, you simply need to upload or copy it into a dialogue box.
Metadefender
Metadefender is another effective threat detection with multiscanning. With over 30 anti-malware engines, Metadefender provides the highest and earliest detection of both known and unknown threats. Unfortunately, it only allows users to upload the file up to 140MB.
Malwarebytes
Malwarebytes is a free and useful tool in anti-malware as it not only stops hackers and malware but also cleans up an infected device. Head into the Malwarebytes app and select a scan, which should then flag the exact apps that contain a threat to your device. Besides, the app allows you to remove the malware directly.
Good luck!