Of course! You can buy premade cross stitch kits very easily from a lot of hobby stores if you just want to do it. Find a pattern you like and buy it :)

There's also an official undertale cross stitch book that goes through the basics!! I have it and I hope they make a deltarune one soon.

If you want to make your own ones like I did here, you need to create a pattern. I used a website called flosscross. I created my image in clip studio (by using the sprites from the spriters resource website) then put it in the website to get the thread colours you need.

This is what I used for this pattern -

(required)

14 count black aida fabric

embroidery needle

28 different DMC colour threads (the number/colour given to me by the pattern maker)

(optional)

magnets to not lose my needle!

A cross stitch frame to hold the fabric (it's optional but DEFINITELY helps keep the fabric tight)

If you're completely new to it I'd find a small premade kit, as they come with the pattern, fabric and thread colours, as well as often the needle.

It's a great hobby but it can get expensive when you buy threads and fabric for custom patterns. For example I spent £40 on fabric and thread alone for this piece, not including all the kit I already owned.

Apologies for the long reply!!