The pedals that came with my 2013 CT700 were dual sided so you could ride either clipless or platform. I didn't use them.
You can try searching on "platform pedals" on eBay. They have them in the 9/16" axle size for as little as $13.
https://www.ebay.com/itm/1-Pair-MTB-....c100005.m1851
I prefer to use ordinary shoes for riding my trike so I use strapless toe clips. Been doing that since 2003 with no problem keeping my feet on the pedals. I think the last pair cost me around $7.
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