Can I achieve multiple endings on one playthrough?

While playing Death’s Door I’ve come to realize that there are multiple endings. I’m not quite sure how many endings there are, but I know there’s at least two, one of which is considered the "True Ending". I have no idea how to achieve this ending, and I’d like to avoid spoiling it for myself. However, I’m also not interested in doing a second playthrough once I finish my first one (at least not right away).

So, ideally, I’d like to just keep playing as I am, and once I beat the "final" boss, then I can worry about trying to achieve this "True" ending (if I haven’t already). However, I’m not sure if that’s possible, since many games will lock you out of the "True" ending past a certain point, forcing you to do a second playthrough.

Can I achieve multiple endings on one playthrough? Is there a "point of no return", past which, I’ll be locked out of achieving the "True" Ending for that playthrough?