AND operator in if: condition

How do I use an && operator in the if: block of a step to check for multiple conditions?

For eg -
if: (${{ matrix.coverage }} == true) && (runner.os == 'Linux')
doesn’t work.

You need to enclose the whole expression in ${{ ... }}, or nothing at all:

if: ${{ (matrix.coverage == true) && (runner.os == 'Linux') }}