We can Sort Portfolio Posts by Date. It’s not the best way to sort them, but as far as there are no good plugins to sort Custom Post Types, it’s better and safer way to do this. ( you can use this plugin https://wordpress.org/plugins/post-types-order/ but in some case it may cause bugs ).
Go to your Dashboard > Portfolio select a post and click on Quick Edit, then change the post date and click on update. This is the way you sort Portfolio Post, but take in mind that posts with newer date will appear first and the with older date will appear next to them, that’s the hierarchy of date sorting. Here is a screenshot how to do that.