They sell covers specifically for covering radio antennas on trunks: https://www.amazon.com/Larsen-HP34-Antenna-Plastic-Hole/dp/B0049D7GBU
Wait, it might be worth looking at these, they aren't specific so idk if they fit https://www.amazon.com/Larsen-HP34-Antenna-Plastic-Hole/dp/B0049D7GBU/ref=mp_s_a_1_4?keywords=antenna+hole+plug&qid=1643133734&sr=8-4