You can not expense this $6000 project since it's cost was over $2,500. You have to enter it as an asset and depreciate it over the next 27.5 years.
When you paid for it doesn't matter. Depreciation doesn't start until the project is placed "in service". Since that did not happen in 2021, you'll enter nothing for this on your 2021 tax return. Instead, you'll enter this $6000 asset on your 2022 return with an in service date of the date the project was completed.
