There are no written mechanics for doing this after character creation.
Unfortunately, there aren't any mechanics (even optional ones) which allow for rearranging the racial ASI after character creation. Tasha's Cauldron of Everything introduced guidance for rearranging racial ASIs during character creation, but is explicit that the guidance is to be applied at 1st level only (Customizing Your Origin, “Ability Score Increases”).
I usually allow my players to do this anyway.
As you play a character through a campaign, it is not at all uncommon for your playstyle to change as you progress. Several times I have had this idea for a character build, and then later decided it really wasn't what I wanted after all. When this happens to my players, I'm pretty generous about allowing them to re-spec their characters - after all, we both want you to have the most fun possible, and if we can make a small change that increases your satisfaction without harming anyone else's, let's make that change. So as a player, just have a conversation with your DM. "Hey DM, so someone else helped me make my character, and as I am learning the game, I am learning what sort of playstyle suits me, I would like to make this attribute score switch that better suits the playstyle I now know I like." I imagine any reasonable DM wouldn't hesitate to let you make that change in this context.
The only time I have vetoed this suggestion was when I felt like a player was taking advantage of my generosity and trying to make situationally beneficial changes to his attribute score distribution. I let him rearrange his attributes during one of the campaign arcs, that made him better suited for the types of enemies I was using, and then he suggested making a similarly beneficial change during another arc that involved a different enemy theme.