I only get max 20 fps in fortnite while in 1080 resolution almost same for other games too so i started playing on 720 p and still i get 30-45 fps. It hasn't been even 1 year since i have bought my dell 5567 laptop. My friend who bought same laptop having lower specs plays games like these getting 60+ fps. The specs of my laptop are:
8 gigs RAM
4 gigs of R7 445M AMD graphics
1 Tb Hard drive
Here is some info to help you with your issues...
First of all, being specific really helps in getting the right answers. Based on the partial info you have given I can only give you generic answers.
INFORMATION REQUIRED WHEN POSTING A QUESTION
Here is some info on your model of laptop. Because I do not know the processor you are using this may not be the exact info for the one you have.
But, from this web page you can search and find specifics for your laptop. This will tell you what kind of performance you should be getting and how it compares to other laptops. It has a section on "Gaming performance".
Dell Inspiron 15 5000 5567-1753 Notebook Review - NotebookCheck.net Reviews
And, here is some info that may help, or at least give you some ideas on how to get better performance from what you have.
Fixes for Game Crashes, Hangs, and Performance Issues
In general, when using a laptop for gaming you need to have the laptop plugged into a wall outlet, running the laptop on the battery puts it into a power savings mode and decreases performance. Set the windows "Power Plan" to high performance. Turn off all power saving features. And stop, or uninstall any programs that run in the background that can eat up computing resources and performance.
Also, setting the games at lower resolution and lower graphics setting will increase performance. Try running games on low or medium graphics rather than high or ultra setting.
I hope this is of some help and good luck!