Clamp with making zoom:1

vegaClamping.json

{
  "$schema": "https://vega.github.io/schema/vega/v5.json",
  "autosize": "pad",
  "padding": 5,
  "width": 200,
  "height": 200,
  "style": "cell",
  "data": [
    {"name": "grid_store"},
    {
      "name": "source_0",
      "url": "data/cars.json",
      "format": {"type": "json"},
      "transform": [
        {
          "type": "filter",
          "expr": "datum[\"Horsepower\"] !== null && !isNaN(datum[\"Horsepower\"]) && datum[\"Miles_per_Gallon\"] !== null && !isNaN(datum[\"Miles_per_Gallon\"]) && datum[\"Cylinders\"] !== null && !isNaN(datum[\"Cylinders\"])"
        }
      ]
    }
  ],
  "signals": [
    {
      "name": "unit",
      "value": {},
      "on": [
        {"events": "mousemove", "update": "isTuple(group()) ? group() : unit"}
      ]
    },
    {"name": "sample", "update": "span(domain(\"x\"))/span(domain(\"y\"))"},
    {"name": "grid", "update": "vlSelectionResolve(\"grid_store\")"},
    {"name": "reachedExtent", "react": true, "update": "span(domain(\"x\")) >= 250"},
    {
      "name": "grid_Horsepower",
      "on": [
        {
          "events": {"signal": "grid_translate_delta"},
          "update": "clampRange(panLinear(grid_translate_anchor.extent_x, -grid_translate_delta.x / width), 0, 250)  "
        },
        {
          "events": {"signal": "grid_zoom_delta"},
          "update": "clampRange(zoomLinear(domain(\"x\"), grid_zoom_anchor.x, grid_zoom_delta), 0, 250)"
        },
        {"events": [{"source": "scope", "type": "dblclick"}], "update": "null"}
      ]
    },
    {
      "name": "grid_Miles_per_Gallon",
      "on": [
        {
          "events": {"signal": "grid_translate_delta"},
          "update": "panLinear(grid_translate_anchor.extent_y, grid_translate_delta.y / height)"
        },
        {
          "events": [{"signal": "grid_zoom_delta"}],
          "force": true,
          "update": "zoomLinear(domain(\"y\"), grid_zoom_anchor.y, grid_zoom_delta)"
        },
        {"events": [{"source": "scope", "type": "dblclick"}], "update": "null"}
      ]
    },
    {
      "name": "grid_tuple",
      "on": [
        {
          "events": [{"signal": "grid_Horsepower || grid_Miles_per_Gallon"}],
          "update": "grid_Horsepower && grid_Miles_per_Gallon ? {unit: \"\", fields: grid_tuple_fields, values: [grid_Horsepower,grid_Miles_per_Gallon]} : null"
        }
      ]
    },
    {
      "name": "grid_tuple_fields",
      "value": [
        {"field": "Horsepower", "channel": "x", "type": "R"},
        {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
      ]
    },
    {
      "name": "grid_translate_anchor",
      "value": {},
      "on": [
        {
          "events": [{"source": "scope", "type": "mousedown"}],
          "update": "{x: x(unit), y: y(unit), extent_x: domain(\"x\"), extent_y: domain(\"y\")}"
        }
      ]
    },
    {
      "name": "grid_translate_delta",
      "value": {},
      "on": [
        {
          "events": [
            {
              "source": "window",
              "type": "mousemove",
              "consume": true,
              "between": [
                {"source": "scope", "type": "mousedown"},
                {"source": "window", "type": "mouseup"}
              ]
            }
          ],
          "update": "{x: grid_translate_anchor.x - x(unit), y: grid_translate_anchor.y - y(unit)}"
        }
      ]
    },
    {
      "name": "grid_zoom_anchor",
      "on": [
        {
          "events": [{"source": "scope", "type": "wheel", "consume": true}],
          "update": "{x: invert(\"x\", x(unit)), y: invert(\"y\", y(unit))}"
        }
      ]
    },
    {
      "name": "grid_zoom_delta",
      "on": [
        {
          "events": [{"source": "scope", "type": "wheel", "consume": true}],
          "force": true,
          "update": "reachedExtent ? clamp(pow(1.001, event.deltaY * pow(16, event.deltaMode)), 0, 1) : pow(1.001, event.deltaY * pow(16, event.deltaMode))"
        }
      ]
    },
    {
      "name": "grid_modify",
      "update": "modify(\"grid_store\", grid_tuple, true)"
    }
  ],
  "marks": [
    {
      "name": "marks",
      "type": "symbol",
      "clip": true,
      "style": ["circle"],
      "from": {"data": "source_0"},
      "encode": {
        "update": {
          "opacity": {"value": 0.7},
          "fill": {"value": "#4c78a8"},
          "tooltip": {
            "signal": "{\"Horsepower\": format(datum[\"Horsepower\"], \"\"), \"Miles_per_Gallon\": format(datum[\"Miles_per_Gallon\"], \"\"), \"Cylinders\": format(datum[\"Cylinders\"], \"\")}"
          },
          "x": [
            {
              "test": "datum[\"Horsepower\"] === null || isNaN(datum[\"Horsepower\"])",
              "value": 0
            },
            {"scale": "x", "field": "Horsepower"}
          ],
          "y": [
            {
              "test": "datum[\"Miles_per_Gallon\"] === null || isNaN(datum[\"Miles_per_Gallon\"])",
              "field": {"group": "height"}
            },
            {"scale": "y", "field": "Miles_per_Gallon"}
          ],
          "size": {"scale": "size", "field": "Cylinders"},
          "shape": {"value": "circle"}
        }
      }
    }
  ],
  "scales": [
    {
      "name": "x",
      "type": "linear",
      "domain": [75, 150],
      "domainRaw": {"signal": "grid[\"Horsepower\"]"},
      "range": [0, {"signal": "width"}],
      "nice": true,
      "zero": false
    },
    {
      "name": "y",
      "type": "linear",
      "domain": [20, 40],
      "domainRaw": {"signal": "grid[\"Miles_per_Gallon\"]"},
      "range": [{"signal": "height"}, 0],
      "nice": true,
      "zero": false
    },
    {
      "name": "size",
      "type": "linear",
      "domain": {"data": "source_0", "field": "Cylinders"},
      "range": [0, 361],
      "zero": true
    }
  ],
  "axes": [
    {
      "scale": "x",
      "orient": "bottom",
      "grid": false,
      "title": "Horsepower",
      "labelFlush": true,
      "labelOverlap": true,
      "tickCount": {"signal": "ceil(width/40)"},
      "zindex": 1
    },
    {
      "scale": "x",
      "orient": "bottom",
      "gridScale": "y",
      "grid": true,
      "tickCount": {"signal": "ceil(width/40)"},
      "domain": false,
      "labels": false,
      "maxExtent": 0,
      "minExtent": 0,
      "ticks": false,
      "zindex": 0
    },
    {
      "scale": "y",
      "orient": "left",
      "grid": false,
      "title": "Miles_per_Gallon",
      "labelOverlap": true,
      "tickCount": {"signal": "ceil(height/40)"},
      "zindex": 1
    },
    {
      "scale": "y",
      "orient": "left",
      "gridScale": "x",
      "grid": true,
      "tickCount": {"signal": "ceil(height/40)"},
      "domain": false,
      "labels": false,
      "maxExtent": 0,
      "minExtent": 0,
      "ticks": false,
      "zindex": 0
    }
  ],
  "legends": [
    {
      "size": "size",
      "gradientLength": {"signal": "clamp(height, 64, 200)"},
      "symbolType": "circle",
      "title": "Cylinders",
      "encode": {
        "symbols": {
          "update": {
            "fill": {"value": "#4c78a8"},
            "shape": {"value": "circle"},
            "opacity": {"value": 0.7},
            "stroke": {"value": "transparent"}
          }
        }
      }
    }
  ]
}