Construct 2 was first released 9 years ago, in February 2011. Back then, Flash was still a dominant technology on the web; Microsoft's latest browser was Intern...
You can have third-part Construct 2 add-ons in Construct 3 by asking their authors to port them using our SDK.
Otherwise, check the Exchange Addon or this dedicated forum (and this topic) to see if a port already exists.
Finally you can try this beta converter.
Once you have a Construct 3 version of the add-on, you can install it using the add-ons manager.