True. There are usually four nylon inserts that match the bolt holes in the plates.
https://www.amazon.com/Snug-Fastener-Stainless-License-SNG253/dp/B07L4BDJTP/ref=zg_bs_15736241_2?_encoding=UTF8&psc=1&refRID=P1J16QTTTT9VM3FMMP2W
https://www.amazon.com/Cruiser-Accessories-81230-Fasteners-Domestic-Stainless/dp/B00032KBFE/ref=sr_1_7?keywords=nylon+license+plate+bracket+inserts&qid=1563514360&s=hi&sr=1-7-catcorr