The Joplin app works fine without Joplin Cloud (it can sync to OneDrive, etc.). I suggest you try it out before purchasing anything!
While the Joplin desktop app does have a rich text editor, I personally use its markdown editor. As I don't frequently use the rich text editor, I'll comment on the markdown editor.
In the desktop app, there are (by default) two columns. Typing **this is some text** causes this is some text to show up in the right column -- the ** characters start/stop a bolded region.
Joplin's flavor of markdown is quite powerful. All of the features you requested are available (but some are rather difficult to type).
I may have misunderstood what you meant by this but Joplin Cloud does not have a web interface through which you can directly create and edit notes. Joplin Cloud is used to synchronise the desktop and mobile clients. You need to use the clients to actually create and manage your notes.
I'm a great fan of the markdown editor, too - but it must be noted that features like changing font size and colours are not available in the rich text editor (as far as I'm aware). HTML/CSS tags can't really be a substitute for daily usage IMO.
Making these features a 'native experience' would probably attract a lot of former Evernote or OneNote users, but would mean a departure from Joplin's 'markdown first' approach, which is part of its charm.
Thank you all for your replies
I have already downloaded and installed Joplin on my computer
I also synced it with Ondrive
I also managed to change the font formatting
To change the font color is more complicated than with Evernot
There is no possibility to go back in case of error
Joplin still has a long way to go on the layout
Evernote under the hood uses custom XML to format notes, so yes, it's way more powerful than Markdown, especially regarding font size/colour formatting and such. Joplin can use HTML tags, but they need to be input manually, so it's not really very user-friendly, especially on mobile. It's also completely inaccessible for "normal" computer users, as they've got no idea what HTML even is.
What do you mean by that? Joplin has note history that's set to 90 days by default, so you can easily revert to multiple previous versions of the same note (see https://joplinapp.org/note_history).