Three Tables in Landscape model at equal distance from each other and the margins

Using geometry : newgeometry beginning a single page plus restoregeometry at the end.

(1) There is no need to change the font size.

(2) Note the empty line before each bigskip.

(3) Added some vertical stretching of the cells (from array).

documentclass{article}

RequirePackage[margin=2in]{geometry}
RequirePackage{pdflscape}
RequirePackage{afterpage}
RequirePackage{array}  

RequirePackage{kantlipsum} % dummy text

begin{document}
    
1. kant[1-3]

afterpage{%
    newgeometry{margin=0.5in}  
    clearpage% Flush earlier floats (otherwise order might not be correct)
    thispagestyle{empty}% empty page style (?)
    begin{landscape}% Landscape page
        begin{table}
            renewcommand{arraystretch}{1.2}
            centering
            %        begin{adjustwidth}{-1cm}{}
            %        begin{adjustbox}{width=20cm}
            %            tiny
            begin{tabular}{|| c | c ||} 
                hline
                textbf{DATABASE 1} & textbf{QUERY 1: QUERY USED PER DATABASE}  [0.5ex] 
                hline
                Scopus & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                EBSCO/CJA & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                CA/WoS & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                ProQuest/IBSS & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                EBSCO/PsycINFO & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                ProQuest/CJD & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                ScienceDirect & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                Wiley & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                JSTOR & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                WorldCat & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
            end{tabular}
            %        end{adjustbox}
            
            bigskip
            %        begin{adjustbox}{width=20cm}
            %            tiny
            begin{tabular}{|| c | c ||} 
                hline
                textbf{DATABASE 2} & textbf{QUERY 2: QUERY USED PER DATABASE}  [0.5ex] 
                hline
                Scopus & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                EBSCO/CJA & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                CA/WoS & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                ProQuest/IBSS & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                EBSCO/PsycINFO & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                ProQuest/CJD & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                ScienceDirect & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                Wiley & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                JSTOR & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                WorldCat & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
            end{tabular}
            %        end{adjustbox}
            
            bigskip
            %        begin{adjustbox}{width=20cm}
            %            tiny
            begin{tabular}{|| c | c ||} 
                hline
                textbf{DATABASE 3} & textbf{QUERY 3: QUERY USED PER DATABASE}  [0.5ex] 
                hline
                Scopus & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                EBSCO/CJA & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                CA/WoS & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                ProQuest/IBSS & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                EBSCO/PsycINFO & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                ProQuest/CJD & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                ScienceDirect & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                Wiley & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                JSTOR & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
                WorldCat & (“police” OR “law enforcement”) AND (“response time?” OR “arrival time?”) 
                hline
            end{tabular}
            %        end{adjustbox}
            %        end{adjustwidth}
            label{table:3}
        end{table}
    end{landscape}
clearpage% Flush page
}

restoregeometry

2. kant[2-5]

end{document}