If I have back taxes I need to file but I don’t have my w-2s for those years because someone stole my identity, should I file this years now or do an extension?

I recommend you go ahead and file for 2023 if you have everything you need to file.  If you don't owe anything there is nothing wrong with filing an extension either if you want more time.  Be sure you do one or the other.

File this years today.

I've been helping a family member with back tax issues. He received useful help by calling the IRS. They told him to keep filing his taxes while he works through past year issues. We filed this year and the last 2 years using freetaxusa online, which was free and had the software for the last 2 tax years and this year.

You can file an affidavit with the IRS about your identity theft.

https://www.irs.gov/newsroom/taxpayer-guide-to-identity-theft

It would also be beneficial for you to verify your identity with the IRS on line where you can look at your tax transcript. They can also issue you an Identity Protection Pin. This PIN would then be required on your tax return and is designed to reduce the risk of someone filing a false return under your name and SSN. 

https://www.irs.gov/payments/your-online-account

https://www.irs.gov/iden[product key removed]-scams/get-an-identity-protection-pin