In many cases, yes. If a token lives on one of the supported networks and can be traded, you can usually buy it through Celia, and it will show up in your portfolio after the purchase.
That said, newer or low-liquidity tokens are more likely to run into issues such as slippage or "not enough liquidity." If that happens, try a smaller amount or try again a little later. And please remember that new and meme tokens can be extremely volatile, always do your own research before buying.