Use the Tags attribute. I've found Scalar will group the methods under those tags perfectly. Something similar to:

[EndpointDescription("Retrieve a paged list of people based on a set of filters")]
[EndpointSummary("List People")]
[Tags("People")]
[HttpGet("people")]
[ProducesResponseType<PagedResultDto<PersonDto>>(StatusCodes.Status200OK, "application/json")]
public async Task<IActionResult> GetPeople([FromQuery] GetPeopleInputDto inputDto)
{ ... }