Get IIS to use .NET Framework > 4.6
Solution 1:
IIS and its App pools already support 4.7, there is nothing you need or can do about this.
Think of .NET CLR Version 4.0 to actually mean .NET CLR Version 4.x, there is only a single CLR 4 installed on your machine and IIS is using it.
No need to do anything, your application should run fine.