Question about ASUS GT-AX11000 Gaming Router WiFi 6

Hello, I am very satisfied with the router myself. However, because of thick walls and too much signal loss in one area of the house, I am considering an AIMesh setup. For this I will have to buy a second router. It probably makes sense if the node is also TRI BAND or? At least that's how it reads best (since the AX11000 is TriBand). Does it matter if the node is Wifi 5 instead of Wifi 6? For example, the predecessor Asus GT-5300 is tri-band but not an AX router. Or would it be better to go for a dual band which corresponds to Wifi6? Thank you in advance and have a nice day. Greetings Cristiano