There is no mods made for GTA V on the PS4 due to it receiving frequent patches, the only gaming systems that has mods for GTA V is the PS3 and XBOX 360, but still, I wouldn't recommend doing this, since it will get your online profile banned if you use it online.
How do I install mods on GTA 5?
Download the ZIP from the web page, extract it to your desktop, open the bin folder, and drag the contents into your GTA 5 installation folder. The Native Trainer file is a little mod menu and is optional. To access even more mods, you're also going to want to download Script Hook V Dot Net from this GitHub page.