For the people with bigger screens who like to see the bigger Thumbnails for the Images, documents and folders etc, here is a trick to change the size (increase or decrease) of the Thumbnail Preview in Windows Explorer.
Increasing the preview size will show a bigger preview of the Thumbnails preventing the need to open the file and see what it contains.
There are two ways to do that:
1. Tweak UI
There is nothing better than Tweak UI if you have it installed in your system. Run Tweak UI, click on Explorer on left and go to Thumbnails section. Change the Size in pixels to any number desired by you.
Increasing the value will increase the size while reducing the value will decrease.
2. Registry Tweak
Navigate to the key HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Explorer. Create a key on the right side named ThumbnailSize with the new Dword Value in between 32 and 256. Value greater than 100 will increase the size and lesser than that will reduce the size.
NOTE: Changes will appear only after you re-open the folder containing the files or after the system restart.