Currently we use the following patten in jstests when we need to figure out if we're in SBE mode or not:

const isSBEEnabled = (() => {
    const getParam = db.adminCommand({getParameter: 1, featureFlagSBE: 1});
    return getParam.hasOwnProperty("featureFlagSBE") && getParam.featureFlagSBE.value;
})();

We should replace this boilerplate code with a helper function instead.

Also, as ian.boros pointed out, this check wouldn't work in a sharded cluster in certain configurations. Namely, when db is using a connection to mongos which doesn't have the feature flag enabled.