Possible to add size option for https://fastpic.ru/
like:reduce size of picture

Thanks

There are already settings for that in themaCreator:

"Settings" -> "Process" -> "Cover" -> "Max cover width".
"Settings" -> "Process" -> "Preview" -> "Max preview width".

These two settings affect the thumbnail size (and all other image hosts).

Make sure to use thumb URL in cover or preview template.

For preview you can as well enable in "Settings" -> "Process" -> "Preview" -> "Try to force maximum thumbnail width to direct image as well".

This will resize the direct URL image to "Max preview width" setting.