Originally posted by 3Tone:

Originally posted by umop-apisdn:

It's already there; with devcommands/debugmode you can fly, never take damage, be invisible to mobs, and build without cost.

https://valheim.fandom.com/wiki/Console_Commands

How do I use devmode

Read the information at the wiki page I linked; it explains it.

If you can't or won't read the wiki for some reason, try watching this video:
https://www.youtube.com/watch?v=bR7KfqpFk-g