You would need to deduce the position of the -
Like this (and then you need to play with the code)
Sub FixTxt()
Dim mySlide As Slide
Dim otxR1 As TextRange
Dim otxR2 As TextRange
Dim hyphPos As Integer
Dim lenTR As Long
Set mySlide = ActivePresentation.Slides(1)
mySlide.Shapes(1).TextFrame.TextRange.Text = "SUMMARY OF AAs RECEIVED AND ACCREDITED " & vbNewLine & "JANUARY - MONTHS-20XX"
lenTR = mySlide.Shapes(1).TextFrame.TextRange.Length
hyphPos = InStr(1, mySlide.Shapes(1).TextFrame.TextRange.Text, "-")
mySlide.Shapes(1).TextFrame.TextRange.Font.Size = 16
mySlide.Shapes(1).TextFrame.TextRange.Font.Bold = True
hyphPos = InStr(1, mySlide.Shapes(1).TextFrame.TextRange.Text, "-")
Set otxR1 = mySlide.Shapes(1).TextFrame.TextRange.Characters(Start:=1, Length:=hyphPos + 1)
Set otxR2 = mySlide.Shapes(1).TextFrame.TextRange.Characters(Start:=hyphPos + 1, Length:=lenTR - hyphPos)
otxR1.Font.Color.RGB = RGB(0, 0, 0) 'or whatever
otxR2.Font.Color.RGB = vbRed
End Sub