I recommend after downloading LSPDFR, go to the website which is Bejojo Plugins and download Stop the pedal, Compulite, Ultimate backup, simple callouts and attempted crime callouts. LSPDFR main basic functions are very basic. The only function for LSPDFR that's good is the backup feature. If you have a controller you push the R3 and you can quickly call for backup. Once you do that, you can add Police vehicles and more callouts from the LSPDFR website. I wouldn't go too crazy with vehicles tho. For me, I have like 8 different police vehicles and several callout plugins. Just because i don't want my game to consistently crash. When you add callout plugins, I suggest installing 2 or 3 at a time then loading into the game to make sure everything is working fine. If it is then add 2 or 3 more. Outside of LSPDFR website plugins and police vehicles, I also have Real California Architecture, Roads of Europe and GTA V remastered installed. These 3, you need to install from GTA V mods.com. I highly recommend watching YouTube videos on these before installing as mods on GTA V mods.com are little different than mods and plugins from LSPDFR.com. That's pretty much it. This way it's not too vanilla but you also don't want overload your game with mods and make sure you DONT play the game online as you will get banned.
https://www.bejoijo.com/
There are ads that pop up, just close them and ignore them
Also, I recommend watching Geoffrey Gamer on how to backup your game. Because rockstar will randomly update the game and when they do you might have to 3-4 days for LSPDFR, RAGE PLUGIN HOOK (which is included in LSPDFR download) and SCRIPT HOOK to update.