Feats vs Ability Score Improvements -- all or nothing?

[odigity]

Confused about whether you have to decide between taking all ASIs vs all Feats, or can you decide level-by-level when the time comes whether to take one or the other?

[Daishain]

It is level by level, assuming your DM rules that feats are available at all of course.

[Cambrian]

You chose every time you achieve the bonus. Keep in mind Feats are not a default option and require DM approval.