ENTERPRISE PRODUCTS PARTNERS marked K-3 but not yet provided

Yes, you should file for an extension if any of your needed tax information, including Schedule K-3, won't be available by the April 18th deadline.

If you file for an extension, include payment of any estimated taxes due. 

See this tax tips article for more information from TurboTax regarding extensions.

See here for the 2022 instructions for Schedule K-3. 

The EPD cover letter states: "The Partnership will report items of international tax relevance to our partners on Schedule K-3. All of our income is effectively connected with a United States trade or business. A limited number of unitholders (primarily foreign unitholders, unitholders
computing a foreign tax credit on their tax return and certain corporate and/or partnership unitholders) may need the detailed information disclosed on Schedule K-3 for their specific reporting requirements."

Unless you are likely to be affected by the above, you can uncheck the K3 box and file as normal.  When it eventually comes out, you can review and amend if needed.

if you are a US citizen, there will be no reportable info on the k-3. uncheck box 16 so you can e-file.  read the transmittal letter that came with the k-1 package.

The Partnership will report items of international tax relevance to our partners on Schedule K-3. All of our income is effectively connected with a United States trade or business. A limited number of unitholders (primarily foreign unitholders, unitholders computing a foreign tax credit on their tax return and certain corporate and/or partnership unitholders) may need the detailed information disclosed on Schedule K-3 for their specific reporting requirements. We do not expect to report either (1) any foreign
income taxes paid or accrued on Schedule K-1, Line 21 or (2) any foreign-derived intangible income.