The Pomodoro technique is pretty cool. You just set a Pomo for say 25 minutes where you just focus on whatever task you are doing. And then when the time is up you could take a 10 minute break, followed by another 25 minutes of solid working. It does not need to be 25 minute intervals by the way you could do it for 1 hour and then take a 15 minute break followed by another 1 hour of hard focused work.

The Forest app is pretty cool for doing Pomodoro as it adds gamification. Basically you do a Pomo and there is a tree growing for your forest. You are now allowed to use your phone because it's a distraction. If you do then your tree dies and it will show up dead in your forest 😂 So as long as you complete your Pomo with distractions you will have a nice beautiful forest. You can even share it on social media.

forestapp.cc

And this app has Pomodoro too but without gamification ticktick.com/home

This website explains it well francescocirillo.com/pages/pomodoro-technique

This is the best way to start with Pomodoro: pomofocus.io