Electrum does not support anything apart from bitcoin.

but similar to bitcoin core, Electrum is also an open source project which people can simply fork and change it to their own specifications.
and many of the altcoin developers have already done that and have created forks of Electrum which are separate projects create by different developers. for example:
for litecoin: https://github.com/pooler/electrum-ltc
for bitcoin cash: https://github.com/fyookball/electrum
Dash: https://github.com/dashpay/electrum-dash
Verge: https://github.com/vergecurrency/electrum-xvg
and a lot more.

you can see from these links that the authors are different but they are forked from the original project which is for bitcoin and is called simply "Electrum" https://github.com/spesmilo/electrum