Python PYQT QLineEdit font size

Try with:

f = self.texteditor1.font()
f.setPointSize(27) # sets the size to 27
self.texteditor1.setFont(f)

Set pointSize property of lineedit font.

self.texteditor1 = QtGui.QLineEdit(self)
font = self.texteditor1.font()      # lineedit current font
font.setPointSize(32)               # change it's size
self.texteditor1.setFont(font)      # set font

Short answer:

self.input_field = QLineEdit()
self.input_field.setFont(QFont('Arial', 15))  # this is what you need!

Full answer:

# import libraries you need!
import sys
from PyQt5.QtWidgets import QMainWindow, QApplication, QWidget, QLineEdit
from PyQt5.QtGui import QFont


class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()

        # some code

        self.input_field = QLineEdit()
        self.input_field.setFont(QFont('Arial', 15))  # this is what you need!

        # some code

        container = QWidget()
        self.setCentralWidget(container)


app = QApplication(sys.argv)

window = MainWindow()
window.show()

app.exec()