As a counterpoint...
Yes, you can play ED without Odyssey but EDO (Elite: Dangerous - Odyssey) adds a lot more content, although it has many detractors.
I am not one of them, however. I really like EDO, enjoy the on-foot missions (inasmuch as the ones I've actually done) and the exobiology stuff (although I'd agree on its grindy nature). You could, in theory, only ever play Odyssey if you wanted to stick to on-foot missions and not even bother with a ship to fly around in. Oddy is nowhere near as bad as some make it out to be. My advice would be: if you have the money, buy the dlc and try it. If you don't like it, don't play it and put the outlay down to experience.
I would reiterate, though, what
@Para Handy said: EDO is very demanding of your hardware, even now after many optimiisations. If you have the oomph, great, if not, you'll find youself dialling back (a lot) on the graphical niceties.
Lastly... EDO, like EDH, needs a lot of practice to git gud. You reep what you sow.
Good luck!
@@@07