How can I redirect to a url in a suitelet? I tried adding a inline html field with a script tag and setting window.location.href but that didn't work.

My guess is that the URL change has to be initiated from a client script to have any effect on the browser. You can attach a client script to your Suitelet form, then some event or action can trigger the URL change from the client side code.

If the url is a NetSuite page, you should be able to use

context.response.sendRedirect()

. If it's external, I think @scottvonduhn's suggestion is your best starting point.

use the N/redirect module, i used that to redirect to sales order in POST

discussed more in the post above https://netsuiteprofessionals.slack.com/archives/C29HQS63G/p1626786006253400