Depends what the pipe is to start with and what it's for. A safe bet for coolant would be self-amalgamating tape, as you can build that up in layers till it's thick enough and is also waterproof as silicon based.

To revise my previous comment, if it's only 1 or 2mm smaller than the hose then it should clamp down ok. Would consider building-up or sleeving if 3 to 5mm too small (dia) but anything more and the correct sized hose is a better bet. I'd also be happier if it were a swaged end to stop the tape working it's way off potentially!!!

I probably wouldn't even both with building up / sleeving for boost pipes - just too much hassle/risk given the cost of a replacement hose.