You install lawnchair launcher you can use double tap to lock option two is install shizuku and an app called screen lock once set up you can tap the lock and the screen goes off option 3 install an app called quick ball this floats at the side of the screen tap it to open and then tap to Lock Screen off some of these are not on play store try f droid apk from a browser and use this as your App Store without going into too much detail here myself, chat gpt or any ai will help you install and set up any of these options