You will find that there are plenty of sites out there that have some if not many works of an artist however, they are often of mixed quality in terms of resolution & size and often do not have the name of the work. Now some artists, which you can find either by actively searching or just stumbling upon, themselves have sites where they post their own work. Although often such images from the sites of such artists will be small in size and/or have copyright watermarks.
[I had a bunch of stuff here but 4chan thinks I am spamming and it keeps thinking it is spam whatever way I format it.]
Something else you may be interested in is https://www.isfdb.org/cgi-bin/ea.cgi?1825
Whilst that does not provide high quality images it does list what publications an artist has done cover art for.