I would not assume that at all. For our kids high school, it was % grade times the weight.
A 95% times 4.0 is a 3.8 uwcgpa. They do not do an A is 4.0. IOWs on their scale, an A being 93%., it is not 4.0 on their transcript, it is 3.72.
Sports have nothing to do with a GPA conversion, what does is some schools use a 7 point scale and others use 10 points. An 85 on a 10 point is a solid B, on a 7 point it is a C. The AFA will place this into the equation. Think about it for my kids if they did a B= 3.0, but for them an 86 is the bottom of the B scale, and an A is 93, they would take a huge hit just because the school district uses a 7 point scale. Meanwhile, the 85 in the 10 point scale would get 3.0 while they got a 2.0. A 92 is a B, or 3.0 if you use the system a B is 3.0. Using the scale from the school profile allows them to change it.
The other conversion factor is weight. Some schools will give weight to honors, others will not. Some will give a 4.5, 5.0 or even 6.0 for AP or college credits. This is why they ask for a school profile, to see the grading scale and weight.
Class ranking matters too, but it is more from a rigor factor and your cgpa. If 30% go Ivy and you rank 15% with a 3.65 cgpa, it looks differently to them than if you rank 15%, 0% go Ivy and you have a 3.90.
~ The first says the school does not hand out A's like presents on Christmas day, the second says they are handing them out at a more liberal rate.
FWIW, our DS's gpa raise on his portal because he attended a school that used a 7 point scale. Have you pulled out your SAT hard copy? Unless things have changed, at the bottom, it will show the 5 schools you had them send your schools to for official admission purposes. They show what your cgpa is according to their rubric. At least the SAT use to do this.