Can I use the paragon assets to make a commercial game?
And if I can, can I modify them as I wish
Yep, you can.
You cannot, however, sell the assets seperate. They have to be part of a project. This goes for all the Marketplace assets.
For more information please look at https://www.unrealengine.com/en-US/marketplace-faq under the Usage Rights section.
I know I can’t sell them just i want to make sure that i can use them freely in a commercial game
You can. However, only if the game has been created with Unreal Engine. You cannot use the assets in for example Unity. Also see Marketplace Guidelines - Unreal Engine and the EULA EULA - Unreal Engine
yeah i know i can use only with ue4