I am regularly asked if students need to take the SAT and the ACT. And the quick answer is No. All you need to do is take a practice test of each test to see which you do better on and which you feel more comfortable taking. Then, focus your efforts on that test and take several practice tests before taking an actual test.
Every college in the country will accept either the SAT or the ACT and they don’t give bonus points for having taken both tests. so there is no advantage to taking both.
The one exception may be for students who prefer the ACT but did well on the PSAT and are a national merit semifinalist. They need to take SAT to be considered for national merit finalist status so they will need to take that test. But, in my experience, those who do well on the PSAT will probably do well on the SAT. If that is the case, even if you prefer the ACT, it may not be necessary to take the ACT if your SAT score is high enough.