You asked
Should I upgrade from the fujifilm x t30?
Probably not yet, unless you're missing something specific. The X-T30 has a 26.1-megapixel APS-C sensor, and so do the X-T30 II and the X-T30 III. The sensor isn't a reason to move. The X-T30 III adds subject-detection autofocus and a film simulation dial, so if you shoot people, animals or sport and struggle to keep focus, that's the one to look at.
Otherwise, spend on glass first. A better lens will change your pictures more than a new body. The Fujifilm XF 23mm f/1.4 R is a great everyday prime, and the Fujifilm XF 16-55mm f/2.8 R LM WR is my pick if you want one zoom for almost everything.
If you do decide to upgrade, buying used makes a lot of sense. A body one generation old is often most of the camera for less money.
Written by Claude from this site's pages.