Buy USDC on Polygon network directly via an exchange and send the funds to your wallet address. Or buy USDC on the Ethereum network and use the Polygon bridge to bridge the funds from Ethereum network to the Polygon network. After which, you can send the funds to your wallet address on the Polygon network.

https://lh6.googleusercontent.com/xZFtsVNDeM7sw98As7Bi_vOYF7_86Yl8_hNzL_Ii2fDDgD7--dSxhyGdyyu9n-ovIO40Ty-MSQ6UQ6Kf9FREjdglBvsyNwE2jcly4Tynz5hhLTzsuXDEc5bRY6Inqrf2tiH4h_9mfqsCJCvH