There are many ways to do that. A candidate needs to look for employers or companies that are eligible to sponsor a US visa.
A candidate with an OPT can look for employers that provide OPT jobs in USA. A candidate can be in OPT after getting permission from the USCIS or having a student visa.
An OPT resume bank is also a way in which employers sponsor visas. One can find such employers online.
OPT candidates in USA are many and are successful in finding sponsorship. A candidate can simply be a student and have many options.
OPT resume database is also an open door. A student with a resume can enter any of the databases and be open for sponsored jobs or visas.
Jobs for international candidates are many but not all employers are eligible to sponsor. When a candidate has OPT, then they have a verified number of employers that can help them in sponsorships as well.
Jobs for OPT students are in their field of study only that is the benefit. A student can look for jobs and sponsorships on OPT job portals as well.
One can go through social media, recruitment portals, and many more for finding such jobs.
OPT candidates in USA have many options for OPT jobs in USA. One can simply get the work authorization and look for sponsorships. One can get the employment authorization document to get jobs with any employer.
Sponsors are found everywhere but one can do research for quick searching and results in the USA.