An aircraft power and propulsion system (200, 400, 500, 600), comprising: an air compressor (12, 202, 612); a heat rejection heat exchanger (204, 424, 622); a combustor (14, 206, 624) positioned to receive compressed air from the air compressor (12, 202, 612) as a core stream and provide thrust to the aircraft; and a closed-loop s-CO2 system (208, 402, 506) having carbon dioxide as a working fluid, that receives power from the combustor (14, 206, 624) and rejects heat via the heat rejection heat exchanger (204, 424, 622) to a cooling stream, the closed-loop s-CO2 system (208, 402, 506) is configured to provide power to: a fan (18, 212, 404, 502, 602, 604) of the power and propulsion system (200, 400, 500, 600) that provides the cooling stream and thrust; the air compressor (12, 202, 612); and auxiliary loads (216, 218, 220, 408, 410, 412) comprising at least one auxiliary power load, at least one auxiliary actuation load, and at least one heating load; and wherein the closed-loop s-CO2 system (208, 402, 506) provides power via the working fluid to the auxiliary loads (216, 218, 220, 408, 410, 412) by being configured to provide a first grade of energy (310, 312, 314) to the auxiliary actuation load to provide a first aircraft function (216, 218, 220, 408, 410, 412); and a second grade of energy (310, 312, 314) being different from the first grade of energy (310, 312, 314) to the auxiliary heating load to provide a second aircraft function (216, 218, 220, 408, 410, 412) being different from the first aircraft function (216, 218, 220, 408, 410, 412). an air compressor (12, 202, 612); a heat rejection heat exchanger (204, 424, 622); a combustor (14, 206, 624) positioned to receive compressed air from the air compressor (12, 202, 612) as a core stream and provide thrust to the aircraft; and a closed-loop s-CO2 system (208, 402, 506) having carbon dioxide as a working fluid, that receives power from the combustor (14, 206, 624) and rejects heat via the heat rejection heat exchanger (204, 424, 622) to a cooling stream, the closed-loop s-CO2 system (208, 402, 506) is configured to provide power to: a fan (18, 212, 404, 502, 602, 604) of the power and propulsion system (200, 400, 500, 600) that provides the cooling stream and thrust; the air compressor (12, 202, 612); and auxiliary loads (216, 218, 220, 408, 410, 412) comprising at least one auxiliary power load, at least one auxiliary actuation load, and at least one heating load; and wherein the closed-loop s-CO2 system (208, 402, 506) provides power via the working fluid to the auxiliary loads (216, 218, 220, 408, 410, 412) by being configured to provide a first grade of energy (310, 312, 314) to the auxiliary actuation load to provide a first aircraft function (216, 218, 220, 408, 410, 412); and a second grade of energy (310, 312, 314) being different from the first grade of energy (310, 312, 314) to the auxiliary heating load to provide a second aircraft function (216, 218, 220, 408, 410, 412) being different from the first aircraft function (216, 218, 220, 408, 410, 412). a fan (18, 212, 404, 502, 602, 604) of the power and propulsion system (200, 400, 500, 600) that provides the cooling stream and thrust; the air compressor (12, 202, 612); and auxiliary loads (216, 218, 220, 408, 410, 412) comprising at least one auxiliary power load, at least one auxiliary actuation load, and at least one heating load; and wherein the closed-loop s-CO2 system (208, 402, 506) provides power via the working fluid to the auxiliary loads (216, 218, 220, 408, 410, 412) by being configured to provide a first grade of energy (310, 312, 314) to the auxiliary actuation load to provide a first aircraft function (216, 218, 220, 408, 410, 412); and a second grade of energy (310, 312, 314) being different from the first grade of energy (310, 312, 314) to the auxiliary heating load to provide a second aircraft function (216, 218, 220, 408, 410, 412) being different from the first aircraft function (216, 218, 220, 408, 410, 412).