Some of the UI can be adjusted in size or length.

Chat screen, for example, can be adjusted if your UI layout is not locked (to hold their positions so you can't accidentally mess them up). You have to first click on the chat log window to make it active (like, not transparent) then hover your mouse on a corner of it. A window resize arrow will appear, now you can change chat window's size.

Same goes with HP bar, EXP bar.

If you like, you can also drag the action bar around and find it a proper position, so it does not collide with your chat window.

Also, the new patch added font size options in in-game Configeration => Log settings => Look at Font Size.