Both OneSearch and many library databases offer the option to limit search results to "Peer-reviewed" works only. Here are a few examples:
Some databases are highly selective and only cover peer-reviewed journals, e.g. Web of Science, Scopus. This means that you will only find peer-reviewed articles when searching on these databases.
How to find high impact peer-reviewed works?
For postgraduate students, you may need to start reading from the top journals in your research field. There are a couple of tools to help you identify the top journals according to certain citation metrics.
Journal Citation Reports (JCR)
ranks journals covered in Web of Science SCIE and SSCI based on Journal Impact Factor (JIF) and a few other metrics. Check out this guide to know how to find top journals in your field based on JIF.
Scopus > Sources
ranks journals covered in Scopus based on CiteScore, SNIP and SJR. Check out this guide to know how to find top journals in your field based on these metrics.