# Plot markers size, shape and placement in ListPlot

I have the following test data

testData1 = Table[{x, Sqrt[x]}, {x, 0, 4, .2}];
testData2 = Table[{x, x^(1/3)}, {x, 0, 4, .2}];
testData3 = Table[{x, x^(1/5)}, {x, 0, 4, .18}];
testData4 = Table[{x, x^(1/9)}, {x, 0, 4, .18}];


I need to plot the above data using ListPlot with different markers placed inside the plot area.

I used the following code

ListPlot[{testData1, testData2, testData3, testData4},
PlotMarkers -> {{\[FilledCircle], 15}, {\[FilledDiamond],
15}, {\[EmptySquare], 15}, {\[FilledSquare], 15}},
PlotLegends -> Placed[{"a", "b", "c", "d"}, {Left, Top}]]


and got the following results In the plot, I am not able to change the size of markers in the plot (data points).

How to change the shape, size of the markers both in plot and in legend?

Clear["Global*"]

testData = Table[{x, Sqrt[x]}, {x, 0, 4, .2}];
testData = Table[{x, x^(1/3)}, {x, 0, 4, .2}];
testData = Table[{x, x^(1/5)}, {x, 0, 4, .18}];
testData = Table[{x, x^(1/9)}, {x, 0, 4, .18}];


If you want the legend labels to scale with the markers:

Manipulate[
ListPlot[testData /@ Range,
PlotMarkers -> (Style[#, ms] & /@ {●, ◆, □, ■}),
PlotLegends -> Placed[
PointLegend[{"a", "b", "c", "d"},
LegendMarkerSize -> ms,
LabelStyle -> {FontSize -> ms}],
Below]],
{{ms, 15, "Marker Size"}, {Small, Medium, Large, 15, 18}}] f[s_String] := Style[s, 18];
ListPlot[{testData1, testData2, testData3, testData4},
PlotMarkers -> {f["\[FilledCircle]"], f["\[FilledDiamond]"],
f["\[EmptySquare]"], f["\[FilledSquare]"]}
, PlotLegends -> Placed[{f["a"], f["b"], f["c"], f["d"]}, {Left, Top}]
, ImageSize -> Large
]
`