The upgrade of the ATLAS tracking detector (ITk) for the High-Luminosity Large Hadron Collider at CERN requires the development of novel radiation hard silicon sensor technologies. For the development of monolithic CMOS sensors for ATLAS we develop fully depleted CMOS monolithic active pixel sensors (DMAPS) to achieve radiation hard CMOS sensors inline with ATLAS ITk specifications. Based on initial studies on prototype sensors we have now developed, produced and tested first full-size depleted CMOS sensors in different CMOS processes along two design approaches: Designs using "small" electrodes were produced in the TowerJazz 180nm imaging process and designs using "large" electrodes were manufactured in AMS 180nm and LFoundry 150nm CMOS processes. The sensors achieve full depletion of the detection layer through a combination of high-resistivity substrates and high bias voltages. The matrix readout architectures are optimised to cope with the LHC 25ns bunch structure and the high hit-rates as expected for the outermost ITk pixel layer. The paper introduces the different design approaches and will present measurements results to assess their performance in view of future applications as radiation hard monolithic CMOS sensors for trackers.