New in landscape photography and lооking for advice on gears

Dear all,

I am looking for a camera for landscape photography. This is quite a new field for me so please forgive my lack of knowledge.

I currently have D500, Pentax k70, and a few old MF film cameras. I used to have ff camera, 5Dii, and 1dsii but long gone. I aim to keep photography for art and joy not aim to be a source of living.

I really enjoyed watching landscape photography from others and thought, Uhm, let's try. The first thing that came to my head is "I need a bigger sensor camera". Maybe medium format? or FF as a minimum. Am I wrong?

I saw this video

https://www.youtube.com/watch?v=l_I673zb_6o&ab_channel=MarkDenney

I make me think, is it worth it to put money in a big sensor body? I am sure people buy them for their job or when they need large print. But do I need to have them to make good photos?

My D500 is not too bad but with the 20.2-Mpix APS-C CMOS sensor. BUT it makes me feel "insecure". I know some pro photographers still use 5D II (22.3 MP) for studio shoots and large prints. But it is a FF body.

So, do I really need a FF at least? if it is the case, with a budget of 2500 Euro. I would go for D850 used. I can sell by D500 and keep only D850

for the same money, I can get a Pentax 645D - 40-megapixel mf. I will use this only for landscape and use the D500 for bird and walk around.

What is your thought on this? or should I just play around with D500 and see it for myself? or does the D500 low MP sensor keep me down?

thank you all

Pics from D500 recently