Is there a tool that can seal paper similar to a paper wrapper on a plastic straw. Or how else can a fold the end that will look neat?
The typical paper straw wrapper has a crimp to the end, along with perhaps a bit of adhesive. A quick search using The Google shows that the arts and crafts world uses paper crimpers. Those tools are rather coarse pitch and would not generate an attractive crimp on a small width of paper.
Additionally, there are a few DIY references for paper crimping, almost off of which appear to use various gears to create the crimping. One of them uses parts taken from a conventional inkjet printer, specifically for the gears within. I've dismantled a number of such printers and can confirm high quantity small pitch gears. All-in-one printers will have a higher gear count, due to the flexibility of operation of such devices.
If you own or have access to a 3D printer, you can also print a set of gears to your liking. You'll have greater options by so doing, as you can determine gear diameter, tooth pitch and gear thickness.
In the simplest form, one could use a set of pliers. Create add-on jaws of any convenient material of sufficient strength, i.e., plastic or wood and carve/cut matching teeth in the jaws. When the pliers are closed, your paper would be formed to match the corrugations.
The latter method is a bit high on the manual creation scale, but also likely to be the lowest cost. 3D printing can be done with a number of online printing services, a local makerspace or sometimes a public library.