i currently have the 18-55 IS II ( Not the STM it seems )
and a 18-200 IS
if they are good enough to start with im more then happy to go with that and spend the money on a good tripod
I'd use what you have. I shoot professional Landscapes, on a full frame camera I usually am in-between 24-35mm for Landscapes. I don't like the super wide look. If I do want a super wide Landscape I'll do the panorama. 18mm on a crop sensor is enough.
Learn how to bracket and do HDR, that will take your Landscapes to the next level. Some people don't like HDR but I do.
Not in camera HDR, but manually doing it. Your camera might let you do 3 brackets at a time I'm not sure. But just do it manually, take as many raw files as you need, on a tripod. Do 2 second timer or a remote. Start easy with like a 3 bracket one, -3ev 0ev and +3 EV eventually you'll get to where you know how many each scene needs. I use anywhere from 6-9 usually.
Then put those together in Lightroom or photoshop. Or if you have a Mac, Aurora HDR is amazing, also has a lightroom plug in, you can do a 30 day trial.
What will then happen is the sky will be exposed, the foreground will be exposed, and there will be a ton of detail. Where as if you just take one picture, the sky will be blown out, unless you use filters and some people prefer that but I like the HDR look.
That will make a bigger difference than picking up a new lens.
As far as tripods, I don't use super expensive tripods but I use really sturdy tripods because of Landscape.
I use the Manfrotto 190GO, it's not a travel tripod but it's light enough to hike and get Landscapes, that's why it has the Go in the name. I use the aluminum one, nowhere near as expensive as the carbon fiber, it has never been an issue.
I then use the XPRO ball head to go on it by manfrotto. This will hold over 22 pounds on that head, which you're not gonna go anywhere near. It also has a good panorama mode.
It also uses the quick release plates so you can use something like a black rapid strap without having to take the strap out to put it on the tripod and back and forth, unless you like a regular camera strap.
But regardless of gear... I'd look into HDR photography. NOT in camera HDR photography. We'd generally just call it bracketing, in order to distinguish.
If you don't have Lightroom, theres a 30 day trial on it too. If you decide you like it, you get Lightroom and photoshop for 9.99 a month. Very cheap to always have the latest versions of both.
Lightroom has a good new panorama feature too. It's not like the old one.