It is interesting to know that a mid-range yet a very budget friendly device like Xiaomi Redmi 5A now have possibilities to support Project Treble through third-party development. This means users of this device can now enjoy custom ROM with regular updates much more easy.
Here in this page, you can download a modified version of TWRP custom recovery to support flashing Android ROM image on Vendor partition. Well, it seems this task is not supported yet by the official version of TWRP for Redmi 5A (codename Riva).
Also check: Red Wolf TWRP for Redmi 5A.
Grab the flash-able .img file of the modified build of Team Win Recovery Project that already supports flashing ROM on the vendor partition. As usual, the file is hosted on our servers via direct hot link.
You will need this Treble-enabled TWRP in case you want to flash latest version of LineageOS v15.1 (Project Treble compatible) ROM based on Android 8.1 Oreo on your device. Well, of course any other custom ROM that supports Project Treble will also need this. Check also: All MIUI and Custom ROMs for Riva.