Most betta's are very curious about anything new added to their tanks,
They will inspect it, pick at it, flare at it, But given a little time they usually adjust and then mostly ignore it.
That has been my experience with most betta's, However occasionally you get one that doesn't accept,
I found me a solution to those guys.
Drop them in one of my larger tanks that's loaded with grow out Mollies, They drive him in a frenzy for a short while, there's just too many of them for him and it's never the same one twice,, After a very short while he gives up his fiesta ways and settles in, Then a few days later he always appreciate a more quiet tank with just a few mates..