#itsmetroi

Some creators give you options for merged files already. I personally go with the single files and go through them with Sims 4 Tray Importer to pick out what I want and don't want. In this example is @peacemaker-ic Hamptons Hideaway Livingroom Collection. His Hamptons collections are one of my favorites in the game, but I do not need all of the pieces so I figure out which ones I need/want and use the Tray Importer to get the rest out of my game. Peacemaker has the options for single files and merged files of this collection for that reason. So you can get exactly what you want. 

Now the reason why I am telling you all this and showing you a set that I am merging is that I personally only merge sets. By merging the sets you are giving your game fewer files to read to load. So you can still have all your CC but your game thinks you have fewer files. As my other tip, I suggest keeping a backup of the mods you are trying to merge in case you mess up. Also, don't merge Game mods and scripts.

Now that Sims 4 Studio has the UnMerge option it makes it easier to merge your packages and unmerge if you make a mistake. Here are some more links that will help you better understand how merging helps and how to do it properly. Piscean Simmer

HOW TO UN-MERGE PACKAGE FILES | The Sims 4 | Sims 4 Studio 

and

HOW TO MERGE CUSTOM CONTENT FILES | SIMS 4 STUDIO | MOD THE SIMS