Can i adjust thumbnail size at infotips, its too small for me
Infotips use the thumbnail size setting in Preferences so you can make them bigger by changing that.
I don't think you can currently make them bigger independently.
In case you haven't found it, Opus also has a preview panel which will show images as large as you want. The button to toggle it is near the end of the default toolbar.
This feature is now available.
Read: Help > File Types > Filetype Editor > Info Tip
Example: {thumbnail:0:256} displays the thumbnail with no border, 256 pixels in size.