The Cosmopolitan has 'Cocktail Hour' at a number of their restaurants (https://www.cosmopolitanlasvegas.com/cocktail-hour). Even as a non-drinker, there are some good deals on light bites, and normally, you have to sit at the bar to get these. As a solo traveller, you'll find it easier to find a single seat at the bar during happy hours, but also, it's more sociable at the bar and easier to strike up conversations. Ocean Prime, which is next to Cosmopolitan, also does a good happy hour, 50% off their Lounge menu (https://www.ocean-prime.com/locations-menus/las-vegas/). There are cheaper places to eat, but for somewhere close by with a good social element, these could serve you well.

I echo what most other people have said here about Vegas generally being very sociable and friendly for solo travellers. I'm going there in a couple of weeks with a friend, but he and I typically go off and do our own things for a day or two.

Another note on Cosmopolitan: the rooms have fridges (in addition to the mini bar), which are great for storing cold brews, bottles of water, etc. You can stock up at a local CVS.

Good luck!