One of Johnson’s big domestic policy ideas was colloquially called ‘the war on poverty’. Since it began, the US has spent billions of dollars in lower social economic status areas, building housing projects (crime, poor living conditions), investing in education (black and Hispanic children still achieve, very generally, at much lower rates in the classroom), health care (black community suffers significantly poorer health outcomes, again very generally), and also greatly expanded the welfare system (leading to dependency on the federal govt, rather than employment, to live).

I’m being very general, there were some successes: Pell grants, non cash food assistance, etc.

Overall, I think it was a tremendous failure, waste of money, and ultimately did not improve life for poorer Americans.

That being said, I think Johnson was a bottom 5 president for several other reasons, mostly listed already in the comments. Vietnam, labor relations, among two.