Brands' opening statement on joining makes clear he has a true European DoF role with full football authority, a massive change from Walsh who was a puffed up Chief Scout. Silva/ANO will be a Head Coach NOT a manager in the traditional British style. A good DoF build close relationships with his HC and works hand in glove with them but the DoF is the senior partner as he is the continuity and he has the long-term strategy/vision.
The DoF sets over-arching football parameters (e.g. is the Everton-way 4-4-2/4-2-3-1/4-3-3/5-4-1...tiki-taka vs. hoofball, high press vs. counter-punch). He also controls training facilities, support staff/medical/sports science and longer-term permanent coaching positions e.g. academy, coaching succession planning. In addition the DoF controls transfer policy e.g. target player ages for first team, valuations, attributes/player types from youth to first team.
The Head Coach is recommended by the DoF (not by the owner/Board) and is expected to fit broadly within the approach set out for the club as a whole by the DoF. The HC has some control over his staff but not total as the DoF may well insist on retaining some staff/succession planning/continuity. The HC controls how to organise training, select teams, motivate/get the most out of the players provided within the broad scheme/ethos set by the DoF. If the HC wants to make significant changes in style and/or target different types of player then this is discussed with the DoF who either agrees, in which case those changes are flowed through the whole structure from youth to first team, or disagrees in which case the HC either accepts and gets on with it or is replaced.
We need to forget everything we think a "manager" does/should do and adapt to this new reality. Of course Silva will have some influence on transfers (positions/attributes he wants) and some ability to tinker with tactics (e.g. varying style/formation during a season for different games) but the overall strategy/ethos, approach and player acquisition/sale decisions rest with Brands who is arguably the single most important figure in the football success of this rebooted Moshiri Everton.