Is there any way to add selected font-weight and create a variable font file?

Question

Is there any way to add selected font-weight and create a variable font file. I need only regular, semibold and bold to reduce file size. i used fontsquirrel for size compression but output was not correct. Or else any other method to combine 3 woff2 font files into single file. There is an online tool for checking website score Yellowlabs and when we check website score there must be only one font file.