Hello,
First of all, I recommend to use the search function, as this question has been asked many times here, including 3 times that I've seen this week. So you will find many answers already in those threads.
But while I'm here I can offer my own recommendations:
All the zoom lenses are good for video, and most lenses that are marked with "LM" towards the end of their name. Some, like the 35mm f/2, focus breathe (appearing to zoom in and out when focusing), but it doesn't seem to be as common as it is among Sony lenses. Fujinon LM (linear motor) optics are particularly good at controlling glare and loss of contrast in backlit scenes, so they are actually very well suited for video. Likely a carryover from that department also being a major supplier of TV broadcast and industrial use lenses.
Among zoom lenses, the XF16-55 is best with an IBIS-equipped body like the T4. It is close to par-focal, and the heavier glass with multiple strong motors is an advantage for video. But it's also the most expensive in that range, and all the zooms are perfectly good. Among the primes, there's unfortunately no good 35mm for video (one isn't LM and the other breathes a lot), but otherwise pick whatever focal length you like and you won't get a bad one.
Fujifilm autofocus isn't quite as "auto-magic" as Canon and Sony. The X-T4 is good, but you will have to control a bit more yourself or do some more retakes than with a Canon or Sony of the same age (2020). But the people who shout and complain about it being "useless" are in my opinion just lazy with it. Take some time to practice, adjust down the focus settings, and use back-button focus to refocus on command instead of letting it constantly doubt whether it's still where it should be, and you will get very good-looking footage.
For technical guides on optimizing settings and technique for modern Fujifilm cameras, I recommend Pal2tech youtube channel, but not until after(!!!) you've spent some time experimenting yourself. Don't let the perfect be the enemy of the good. Good luck and enjoy : )