This kind of thing?
10 Gallon Aqarium Divider with Suction Cups - Fish Tank Divider Perfect for Betas https://www.amazon.com/dp/B079NXNZ8L/ref=cm_sw_r_cp_api_i_OtLIFbBQHMW0T Amazon, I bought 2, and sawed off the sides of the suction cups I didn’t want.