Young children should/will be tested at one of their normal pediatric "well check" visits.

If you live in an older house (let's say built before 1980) check for cracking/peeling paint on woodwork. Paint on walls is less likely to be peeling in my experience, but of course be on the lookout for that also.

By now, any lead paint has probably been painted over, so if everything looks solid it's best to leave it alone.

You can buy inexpensive lead paint test kits at any hardware/home improvement store.

Also be aware of older venetian blinds, some of these can contain lead.

The Tompkins County Health Department expects pediatricians or family doctors to test kids for lead at age 1 and 2.

https://tompkinscountyny.gov/health/lead/index

Here is what the CDC says

https://www.cdc.gov/nceh/lead/prevention/blood-lead-levels.h...

It is an easy test, ask your primary care provider.

If you're in a major city, check if they have an existing program. Several of the cities near me with older housing stock do (SF bay area).

Testing the tap water comes to mind