Can I withdraw money from my Apple Cash

You can transfer it to a debit card or bank account. See the following Apple Support article for information on transferring: Transfer money in Apple Cash to your bank account or debit card - Apple Support

Some other things you can do with Apple Cash:

Send it to someone: Send and receive money with Apple Cash - Apple Support

Use it to buy something where Apple Pay is accepted: Make purchases using Apple Pay - Apple Support

Use it to make a payment on your Apple Card balance (if you have an Apple Card): How to make Apple Card payments - Apple Support