Is there an update for epson scan for 32 bit Catalina for Apple macbook air having 32 bit Catalina OS?

Catalina is not and has never been a 32 bit OS - only 64 Bit OS and as already mentioned only supports 64 Bit Applications. Suggest using the Epson Site and input the exact model of Scanner and see if there is a Catalina Specific Driver

catalina is not able to run 32bit apps

you need to find a 64bit epson scan app

read

macOS Catalina 10.15 Support | Epson US