Yes, you can. The button you want is the pencil button under your post:
If you don’t see that, you may need to first click a […] image shown here:
…and then it shows a bunch more options, including a pencil button to do editing:
Definitely not clear for new users, but hopefully everyone figures it out over time or sees this!
Note: You have a bit of time to edit your post/comment without it showing that you edited it. After that, it shows an edit history. At some point, like a couple of days(?), it doesn’t let you edit it anymore at all. These are all time settings I can change