An employer or an individual person may apply for a DBS check. Further information is available on the UK government website at: https://www.gov.uk/find-out-dbs-check. This includes how you can find out what level of DBS you may need and has a link to apply for a basic check for yourself.
You can use other services, such as https://crbdirect.org.uk/ which is an independent service not affiliated to the Government, or if you are an employer, you may be able to register with a company such as: https://www.sonographersmedical.com/dbs-crb-checks/
For both standard and enhanced checks from 28th November 2020 a change was made such that childhood cautions are no longer disclosed, and a rule that meant someone with more than one conviction had all their convictions disclosed, regardless of offence or length of time, has been abolished. For further information on this please see: www.unlock.org.uk/policy-issues/specific-policy-issues/filtering/what-will-be-the-impact-of-the-changes-to-filtering/
The Disclosure Calculator
The Disclosure Calculator is a web tool that can be used to find out when a criminal record becomes spent under the Rehabilitation of Offenders Act 1974 (ROA). https://hub.unlock.org.uk/disclosure-calculator/ This applies to England and Wales