Can I just file for an extension

If you are receiving a tax refund there is no need for you to file an extension.  You can file your 2023 tax return at any time on or before April 15, 2027 without penalty since you are receiving a refund.

Additionally, filing an extension for 2023 expired after April 15, 2024.

No, you cannot request an extension now.  If you needed an extension you had to send in the request no later than April 15, 2024.   It is too late.   But....if you are getting a refund or will not owe tax, it will be okay--there is no penalty for filing after the deadline if you do not owe.  You say you are getting a refund.  You do not need an extension .   Prepare your 2023 return and file it when you have it ready.  E-fiing will be open until October 15.  After that, e-filing for 2023 will shut down and you cannot e-file.