I have magento 2.2.6 website in aws server (EC2).I am connecting to that aws sever using ssh in cmd From my windows 10 computer . I have a directory (folder) named Var in aw
You can use du -sh to get folder size. More examples are available here.
You can use 'ls -halt' to sort files by date or reverse it using ls -haltr, you your can read this stackexchange link on how to sort by date using various other ways.
You can use find . -type f -size +1000M to find files lager than 1GB, or if you want to limit it to the current folder you can use find . -maxdepth 1 -type f -size +1000M. You can read this link on how to find files larger or smaller than.