Bug bounties are a great way to get your feet wet. I've seen many devs (especially web devs) have a lot of success hacking on websites that are built with frameworks they are familiar with. I would recommend checking out Bugcrowd or Hackerone to get started.
Besides that, there are a ton of great online courses such as PWK/OSCP, and labs (HacktheBox).
Besides that, there are a ton of great online courses such as PWK/OSCP, and labs (HacktheBox).