1. You're still using old catalyst driver (the one published in 2019 on msi website)
You start amd settings lite (install it from windows store, it's free - link available on msi's support page for this laptop, in utility section).
In one of the tabs (probably system or preferences), you will find another tab called "switchable graphics"
In this tab, you can tell wich GPU must be used for which exe file.
Note: Highest performance means use better gpu (the 5500m); better autonomy means use crappy gpu (the vega one included in the cpu)
This solution doesn't work if you're using amd driver published in july 2020 or a more recent version.
2. You're using the amd driver published in july 2020 or a more recent version
You will have to use window's feature for that.
I really hope, amd will update its support page to tell the second option as the first has dissapeared !