If its a Wifli RD then yes and if it isn't then no. You probably need to find out which RD you have.

From speaking with my LBS today it seems you can buy a Wifli eTap RD kit but its not cheap!

• SRAM RED® eTap Rear Derailleur
  The SRAM RED® eTap® rear derailleur executes shifts the instant you demand. Wirelessly. It’s easy to set up, clean in appearance and delightfully uncomplicated. Mechanical necessities such as a carbon pulley cage, ceramic pulley bearings, and anodized alloy artfully blend with proprietary electronic advancements to deliver a shifting wonder
  
• Compatible with SRAM RED® eTap shift/brake controls
• SRAM 11-speed compatible, 28t maximum capacity
• WiFLiâ„¢ option fits up to 32t
• SRAM eTap® shift logic
• Wireless connection via AIREAâ„¢ network for fast and clean installation
• Exact Actuationâ„¢ provides precise gear selections
• Designed to work with SRAM PowerGlideâ„¢ and PowerdomeXâ„¢ cassettes

Careful. Not all eTap is WifLi. You need the mid-cage (shown on the right here)


https://www.sram.com/...1b1f8x105s2ph0ca88f8

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My latest book: "Out of the Melting Pot, Into the Fire" is on sale on Amazon and at other online and local booksellers

Ok. I think I am confused. I thought WiFli was the wireless etap stuff but it's not. it appears my rear is just sram red etap not wifli

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My other car is a Felt. DFL>DNF>DNS.

"There will come a day you won't be able to do this, today is not that day."

I think I am confused about your confusion :-)
I have a Wifli etap

Someone might chime in that has setup a bike with the regular rear derailleur with a 32 in case you have that one.

I doubt anyone will, because I don't think it works well at all. You might get by if you install a digirit or ceramicspeed pulley system. But that costs nearly as much as new RD.

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My latest book: "Out of the Melting Pot, Into the Fire" is on sale on Amazon and at other online and local booksellers

I wondered if it would and why I ordered the Wifli as soon as it was available. I was seeing posts elsewhere by guys saying it works, but when we set up my bike with Wifli it pulled the lower pulley wheel way forward. We tried it again with a new chain and got it to the point in the picture link above. After that I wondered how others got a regular rear to work with a 32.

putting aside your confusion about Wifli and etap...I think you could probably run a regular (non-Wifli) etap with a 30 tooth cassette. Once you hit 32t, I think it gets dicier and probably need to switch to the Wifli etap RD