you can, but not the way you think of
long term, you need hundreds of accounts, do propaganda, have your own subreddits and a way to manage accounts quickly to influence masses... too much to say about this anyway, it's a bit complicated.
short term, you can get an account, order from fiverr a pic of a girl/man writing on a piece of paper with a selfie, AMA(ask me anything) user xyz date etc.. and you can go with titles like "I'm the owner of x site and etc..." or "My name is GG and I work as x for y company" (in description you can add proof of the fiverr pic, add your site/s etc,, make sure you monetize whatever you want on your site, never dump your aff. products in there...reddit users are not as dumb as the YT community) then you upvote quickly that thread and use other accounts to ask questions which you also will answer with your account/s... most people are lurkers which is the point, some will join the conversation too. travel/booking niche does wonder. but also niches in health.
obviously you want to do the short term, as for the long term... you need brains of steel and patience. if there's anyone who wants to play with reddit and has time on their hands, let me know.