https://wiki.lineageos.org/devices/herolte/install

Primero hay que instalar un custom recovery

Instalamos Heimdall y nos bajamos el custom recovery. El samsung S7 es herolte:
  twrp-3.3.1-0-herolte.img.tar
  d7f03ba5bb06781328df34dc1548d8a9  recovery.img

Iniciamos en modo Recovery:

pulsar volumen_UP+home+power

Pulsamos WIPE / Advanced Wipe/ System,data y cache. Mmovemos Swipe to Wipe

Reiniciamos el movil y cuando esté apagado pulsamos volumen_DOWN+home+power porque sinó, carga la caché otra vez.

Nos saldrá pantalla turquesa que pone Downloading

Conectamos el cable y lanzamos el comando:

./heimdall flash --RECOVERY recovery.img --no-reboot
<code>
Heimdall v1.4.2

Copyright (c) 2010-2017 Benjamin Dobell, Glass Echidna
http://www.glassechidna.com.au/

This software is provided free of charge. Copying and redistribution is
encouraged.

If you appreciate this software and you would like to support future
development please consider donating:
http://www.glassechidna.com.au/donate/

Initialising connection...
Detecting device...
Claiming interface...
Setting up interface...

Initialising protocol...
Protocol initialisation successful.

Beginning session...

Some devices may take up to 2 minutes to respond.
Please be patient!

Session begun.

Downloading device's PIT file...
PIT file download successful.

Uploading RECOVERY
100%
RECOVERY upload successful

Ending session...
Releasing device interface...
</code>


Grabamos la imagen y los gapps en la SD.

Arrancamos y pulsamos install
  f2c9d9a8962263c0c0d1f214f9f8781f  open_gapps-arm64-10.0-nano-20201121.zip
  03ef5ab5fe8401345c66ae20100773d7  lineage-17.1-20201110-UNOFFICIAL-herolte.zip
  de506b3264f96c6b05daeff58b6300a9  lineage-18.1-20201223-UNOFFICIAL-herolte.zip