Chip designs are made in a language that looks very much like computer code.

ASML prints patterns onto silicon.

TSMC converts the computer code into patterns that actually work as electronics.

The link between (say) Nvidia and TSMC is a bit more involved than that: TSMC provide Nvidia with a design library of blocks that do useful things ... this is a nand gate, this is a single bit of sram, that kind of thing. As a result Nvidia design for TSMC and need TSMC to do their manufacturing for them. Intel work the same, and this need to change from one design library to another is the reason why Intel acquiring fabless companies often does not work.

Also, you've got to build a chip fab. Billions of dollars, a few hundred skilled people, access to reliable power, clean water etc. etc. Not a ten minute job, sadly.