The most reliable way to check peer-reviewed status is to read the journal's Instructions to Authors. If you are on the journal article's site click the journal title name. A section like About this Journal might note peer-review but the Instructions to Authors should give details about whether some articles are solicited and reviewed only by an editor and some are peer-reviewed.
Quick methods that may overlook that some journals have solicited review articles are to:
The article will usually indicate the authors' affiliation, sometimes by department and sometimes include the degrees and specialty certification designations. The text of the paper may describe the expertise of the team members. Sometimes there will be a link to the author's Scopus record which will give an overview of the author's affiliation, publications and the number of times articles have been cited. Looking at the author's institution directory can often provide details about role, education, positions, department, etc.
The article may also describe any author's conflicts of interest.