You can’t install and run x86 native on ARM and that command
is a native ARM comand in your case.
What interpreter? Is it capable to install from other repos?
Maybe you take a look at this GitHub - ptitSeb/box64: Box64 - Linux Userspace x86_64 Emulator with a twist, targeted at ARM64 Linux devices - read their documentation there, and the box64 is in the Manjaro ARM repos, but you will actually need box86 to try to run Steam trough on your ARM device/system.