You can take dual enrollment classes without HS credit and would have a separate transcript. Some schools ask for all transcripts and others don’t. Community colleges in our area don’t offer anything beyond calculus so you would probably need a 4 year college for the math classes you are interested in. If you plan on going to a highly competitive school you won’t get transfer credit anyway so it’s good you are just taking them to learn. MIT only lets you skip calc for example, UChicago makes you take an in house test for placement in math with only elective credit for AP or DE, etc